Celestin Apprentice 5/Apprentice-Release5.iso/Environments/PowerMacOberon feb96/Source/TextFrames1.Mod

Oberon Text | 1996-01-29 | 63.0 KB | 1,400 lines | [TEXT/.Ob4]

Syntax10.Scn.Fnt
Syntax10i.Scn.Fnt
Syntax10b.Scn.Fnt
Syntax8.Scn.Fnt
Syntax12.Scn.Fnt
Arial12.Scn.Fnt
FoldElems
MODULE TextFrames;    (** CAS/MH/HM 12.10.1993 / mf 12.10.93 / mah 26.7.94 **)
    IMPORT Macintosh, Modules, Input, Display, Fonts, Viewers, Oberon, MenuViewers, Texts, ScrollBars, Files;
    CONST
        (** update message IDs **)
            replace* = 0; insert* = 1; delete* = 2;
        (** units **)
            mm* = 36000;  Unit* = 10000;
        (** parc options **)
            gridAdj* = 0;  leftAdj* = 1;  rightAdj* = 2;  pageBreak* = 3;    twoColumns* = 4;
        (** maximum number of TAB stops in Parc **)
            MaxTabs* = 32;
        AdjMask = {leftAdj, rightAdj};
        TAB = 9X; CR = 0DX; DEL = 7FX; CRSL = 0C4X; CRSR = 0C3X; LF = 0A4X; BRK = 0B9X; ShiftBRK = 0B8X;
        CRSU = 0C1X; CRSD = 0C2X; DELRIGHT = 008X;        (*<< mah *)
        EOL = 093X; HOME = 091X; PGUP = 0ACX; PGDN = 0ADX; (*<< mah *)
        AdjustSpan = 30; MinTabWidth = 3 * mm; StdTabWidth = 4 * mm;
        rightKey = 0; middleKey = 1; leftKey = 2; cancel = {rightKey, middleKey, leftKey};
        trackWord = 3; trackLine = 4;
    TYPE
        Parc* = POINTER TO ParcDesc;
        ParcDesc* = RECORD (Texts.ElemDesc)
            left*: LONGINT;    (** distance from (F.X + F.left); in units **)
            first*: LONGINT;    (** first line indentation from P.left; in units **)
            width*: LONGINT;    (** parc width; in units **)
            lead*: LONGINT;    (** distance to previous line; in units **)
            lsp*: LONGINT;    (** line spacing of text after P; in units **)
            dsr*: LONGINT;    (** descender of text after P; in units **)
            opts*: SET;
            nofTabs*: INTEGER;
            tab*: ARRAY MaxTabs OF LONGINT    (** in units **)
        END;
        TextLine = POINTER TO TextLineDesc;
        Location* = RECORD
            org*, pos*: LONGINT;
            x*, y*, dx*, dy*: INTEGER;
            line: TextLine
        END;
        TextLineDesc = RECORD
            next: TextLine;
            eot: BOOLEAN;                (* contains end of text *)
            indent: LONGINT;                (* line indentation in units *)
            w, h, dsr: INTEGER;            (* bounding box clipped to frame (w including indent) *)
            w0, nob: INTEGER;            (* unclipped width (including indent), number of contained blanks: nob > 0 if text line wraps around *)
            org, len, span: LONGINT;    (* len ... characters w/o; span ... w/ trailing CR or white space, if any *)
            P: Parc;                            (* last parc before this text line *)
            pbeg: LONGINT                (* position of P *)
        END;
        Frame* = POINTER TO FrameDesc;
        FrameDesc* = RECORD (Display.FrameDesc)
            text*: Texts.Text;
            org*: LONGINT;
            col*, left*, right*, top*, bot*: INTEGER;
            markH*: INTEGER;    (** position of tick mark in scroll bar (< 0 => no tick mark) **)
            barW*: INTEGER;    (** scroll bar width **)
            time*: LONGINT;    (** selection time **)
            hasCar*, hasSel*, showsParcs*: BOOLEAN;    (** caret/selection present; parcs visible **)
            carloc*, selbeg*, selend*: Location;
            focus*: Display.Frame;    (** frame of nested element if this element contains the focus **)
            trailer: TextLine    (* ring with trailer and header *)
        END;
        DisplayMsg* = RECORD (Texts.ElemMsg)
            prepare*: BOOLEAN;
            fnt*: Fonts.Font;
            col*: SHORTINT;
            pos*: LONGINT;    (** position in host text **)
            frame*: Display.Frame;    (** ~prepare => host frame **)
            X0*, Y0*: INTEGER;    (** ~prepare => receiver origin in screen space **)
            indent*: LONGINT;    (** prepare => width already consumed in line, in units **)
            elemFrame*: Display.Frame    (** optional return parameter **)
        END;
        TrackMsg* = RECORD (Texts.ElemMsg)
            X*, Y*: INTEGER;
            keys*: SET;
            fnt*: Fonts.Font;
            col*: SHORTINT;
            pos*: LONGINT;    (** position in host text **)
            frame*: Display.Frame;    (** host frame **)
            X0*, Y0*: INTEGER    (** receiver origin in screen space **)
        END;
        FocusMsg* = RECORD (Texts.ElemMsg)
            focus*: BOOLEAN;    (** whether to focus or to defocus **)
            elemFrame*: Display.Frame;    (** focus/defocus target **)
            frame*: Display.Frame    (** host frame **)
        END;
        NotifyMsg* = RECORD (Display.FrameMsg)
            frame*: Display.Frame    (** host frame **)
        END;
        UpdateMsg* = RECORD (Display.FrameMsg)
            id*: INTEGER;
            text*: Texts.Text;
            beg*, end*: LONGINT
        END;
        InsertElemMsg* = RECORD (Display.FrameMsg)
            e*: Texts.Elem
        END;
        SelectMsg = RECORD (Display.FrameMsg)
            text: Texts.Text;
            beg, end: LONGINT;
            time: LONGINT
        END;
        ScrollBarElem = POINTER TO ScrollBarElemDesc;                    (* CM 19.07.94 *)
        ScrollBarElemDesc = RECORD (ScrollBars.ScrollBarElemDesc)
        END;
        menuH*, barW*, left*, right*, top*, bot*: INTEGER;
        defParc*: Parc;
        (*shared globals => get rid off in a later version?*)
        W, W0: Texts.Writer;
        B: Texts.Buffer;
        P: Parc;
        pbeg: LONGINT;    (*inv T[pbeg] = P*)
        R: Texts.Reader;
        nextCh: CHAR;    (*inv Base(R) = T => T[Pos(R)-1] = nextCh]*)
        par: Oberon.ParList;
        neutralize: Oberon.ControlMsg;
        scrollBar: ScrollBarElem; used: BOOLEAN;                (*CM 08.08.94*)
    PROCEDURE Min (x, y: INTEGER): INTEGER;
    BEGIN IF x < y THEN RETURN x ELSE RETURN y END
    END Min;
    PROCEDURE Max (x, y: INTEGER): INTEGER;
    BEGIN IF x > y THEN RETURN x ELSE RETURN y END
    END Max;
    PROCEDURE MarkMenu (F: Frame);
        VAR R: Texts.Reader; V: Viewers.Viewer; T: Texts.Text; ch: CHAR;
    BEGIN V := Viewers.This(F.X, F.Y);
        IF (V IS MenuViewers.Viewer) & (V.dsc IS Frame) & (F # V.dsc) THEN
            T := V.dsc(Frame).text;
            IF T.len > 0 THEN Texts.OpenReader(R, T, T.len - 1); Texts.Read(R, ch) ELSE ch := 0X END;
            IF ch # "!" THEN Texts.Write(W0, "!"); Texts.Append(T, W0.buf) END
        END
    END MarkMenu;
    (* Element Subframes *)
    PROCEDURE InvertBorder (F: Display.Frame);
    BEGIN
        Display.ReplPattern(Display.white, Display.grey1, F.X-1, F.Y-1, F.W+2, 1, Display.invert);
        Display.ReplPattern(Display.white, Display.grey1, F.X-1, F.Y+F.H, F.W+2, 1, Display.invert);
        Display.ReplPattern(Display.white, Display.grey1, F.X-1, F.Y, 1, F.H, Display.invert);
        Display.ReplPattern(Display.white, Display.grey1, F.X+F.W, F.Y, 1, F.H, Display.invert)
    END InvertBorder;
    PROCEDURE InvalSubFrames (F: Frame; x, y, w, h: INTEGER);    (* removes and suspends all subframes partly in (x, y, w, h) *)
        VAR p, f: Display.Frame; msg: MenuViewers.ModifyMsg;
    BEGIN
        IF (w > 0) & (h > 0) THEN f := F.dsc;
            IF f # NIL THEN p := f; f := p.next END;
            WHILE f # NIL DO
                IF (f.X < x + w) & (f.X + f.W > x) & (f.Y < y + h) & (f.Y + f.H > y) THEN p.next := f.next;
                    msg.id := MenuViewers.reduce; msg.dY := 0; msg.Y := f.Y; msg.H := 0;
                    f.handle(f, msg)
                ELSE p := f
                END;
                f := p.next
            END;
            f := F.dsc;
            IF (f # NIL) & (f.X < x + w) & (f.X + f.W > x) & (f.Y < y + h) & (f.Y + f.H > y) THEN F.dsc := F.dsc.next;
                msg.id := MenuViewers.reduce; msg.dY := 0; msg.Y := f.Y; msg.H := 0;
                f.handle(f, msg)
            END
        END
    END InvalSubFrames;
    PROCEDURE ShiftSubFrames (F: Frame; oldY, newY, h: INTEGER);    (* shift (F.X, oldY, F.W, h) to (F.X, newY, F.W, h) *)
        VAR f: Display.Frame; msg: MenuViewers.ModifyMsg;
    BEGIN
        IF oldY > newY THEN InvalSubFrames(F, F.X, newY, F.W, oldY - newY)
        ELSE InvalSubFrames(F, F.X, oldY + h, F.W, newY - oldY)
        END;
        f := F.dsc;
        WHILE f # NIL DO
            IF (f.Y < oldY + h) & (f.Y + f.H > oldY) THEN INC(f.Y, newY - oldY);
                msg.id := MenuViewers.reduce; msg.dY := 0; msg.Y := f.Y; msg.H := f.H;
                f.handle(f, msg)
            END;
            f := f.next
        END
    END ShiftSubFrames;
    PROCEDURE NotifySubFrames (F: Frame; VAR msg: Display.FrameMsg);
        VAR p, f: Display.Frame;
    BEGIN f := F.dsc;
        IF msg IS NotifyMsg THEN msg(NotifyMsg).frame := F END;
        WHILE f # NIL DO p := f; f := f.next; p.handle(p, msg) END
    END NotifySubFrames;
    (* Display Primitives *)
    PROCEDURE DrawCursor (x, y: INTEGER);
    BEGIN Oberon.DrawCursor(Oberon.Mouse, Oberon.Arrow, x, y)
    END DrawCursor;
    PROCEDURE TrackMouse (VAR x, y: INTEGER; VAR keys, keysum: SET);
    BEGIN Input.Mouse(keys, x, y); keysum := keysum + keys; DrawCursor(x, y)
    END TrackMouse;
    PROCEDURE EraseRect (F: Frame; x, y, w, h: INTEGER);
    BEGIN
        Display.ReplConst(F.col, x, y, w, h, Display.replace); InvalSubFrames(F, x, y, w, h)
    END EraseRect;
    PROCEDURE Erase (F: Frame; x, y, w, h: INTEGER);    (*RemoveMarks optimization*)
    BEGIN
        IF h > 0 THEN Oberon.RemoveMarks(x, y, w, h); EraseRect(F, x, y, w, h) END
    END Erase;
    PROCEDURE Shift (F: Frame; oldY, newY, h: INTEGER);    (*RemoveMarks optimization*)
    BEGIN
        IF (oldY # newY) & (h > 0) THEN
            Oberon.RemoveMarks(F.X + F.left, Min(oldY, newY), F.W - F.left, Max(oldY, newY) + h);
            Display.CopyBlock(F.X + F.left, oldY, F.W - F.left, h, F.X + F.left, newY, Display.replace);
            ShiftSubFrames(F, oldY, newY, h)
        END
    END Shift;
    PROCEDURE InvertCaret (F: Frame);
        VAR loc: Location; bot: INTEGER;
    BEGIN loc := F.carloc; bot := loc.y + loc.line.dsr - 6;
        Display.CopyPatternC(F, Display.white, Display.hook, loc.x, bot, Display.invert)
    END InvertCaret;
    PROCEDURE InvertRect (F: Frame; x, y, w, h: INTEGER);    (*clips to right and bottom frame margin*)
    BEGIN
        IF x + w > F.X + F.W - F.right THEN w := F.X + F.W - F.right - x END;
        IF y >= F.Y + F.bot THEN Display.ReplConst(Display.white, x, y, w, h, Display.invert) END
    END InvertRect;
    PROCEDURE InvertSelection (F: Frame; beg, end: Location);
        VAR t: TextLine; ex, rx, w, py: INTEGER;
    BEGIN
        rx := F.X + F.W - F.right; t := end.line;
        IF t.eot OR (end.pos <= t.org + t.len) THEN ex := end.x ELSE ex := rx END;
        IF beg.line = end.line THEN InvertRect(F, beg.x, beg.y, ex - beg.x, beg.line.h)
        ELSE t := beg.line; py := beg.y; w := F.W - F.left - F.right;
            InvertRect(F, beg.x, py, rx - beg.x, t.h); t := t.next; DEC(py, t.h);
            WHILE t # end.line DO InvertRect(F, F.X + F.left, py, w, t.h); t := t.next; DEC(py, t.h) END;
            InvertRect(F, F.X + F.left, py, ex - (F.X + F.left), t.h)
        END
    END InvertSelection;
    PROCEDURE CoordToPos (F: Frame; mh: INTEGER): LONGINT;
        VAR h: INTEGER;
    BEGIN h := F.H - 1;
        IF h > 0 THEN RETURN (h - mh) * F.text.len DIV h ELSE RETURN 0 END
    END CoordToPos;
    PROCEDURE ShowBar (F: Frame; botH, topH: INTEGER);
    BEGIN
        IF (F.left > F.barW) & (F.barW >= barW) THEN                (*CM 08.08.94*)
            scrollBar.F := F;
            scrollBar.SetDim(F.X, F.Y, F.barW -1, F.H);
            IF (F.text = NIL) OR (F.trailer = NIL) THEN  scrollBar.CalculateSliderDim(0,0,0)
            ELSE scrollBar.CalculateSliderDim(F.text.len, F.org, F.trailer.org + F.trailer.len)
            END;
            scrollBar.Draw;
            Display.ReplConst(Display.white, F.X + F.barW - 1, F.Y + botH, 1, topH - botH, Display.replace)
        END
    END ShowBar;
    PROCEDURE ShowTick (F: Frame);    (* removes global marks as needed *)
        VAR h, mh: INTEGER; len: LONGINT;
    BEGIN
        h := F.H - 2; len := F.text.len;
        IF len > 0 THEN mh := SHORT(h - h * F.org DIV len) ELSE mh := h END;
        Oberon.RemoveMarks(F.X, F.Y, F.barW, F.H);                (*CM 08.08.94*)
        IF ~used & (F.left > F.barW) & (F.barW >= barW) THEN
            scrollBar.F := F;
            scrollBar.SetDim(F.X, F.Y, F.barW -1, F.H);
            scrollBar.CalculateSliderDim(F.text.len, F.org, F.trailer.org + F.trailer.len);
            scrollBar.DrawSlider(FALSE)
        END
    END ShowTick;
    PROCEDURE Mark* (F: Frame; mark: INTEGER);
    BEGIN
(*        Erase(F, F.X, F.Y, F.barW - 1, F.H); F.markH := -1;
        IF mark > 0 THEN ShowTick(F) END *)
    END Mark;
    (** Parcs **)
    PROCEDURE ParcBefore* (T: Texts.Text; pos: LONGINT; VAR P: Parc; VAR beg: LONGINT);
        VAR R: Texts.Reader;
    BEGIN Texts.OpenReader(R, T, pos + 1);
        REPEAT Texts.ReadPrevElem(R) UNTIL R.eot OR (R.elem IS Parc);
        IF R.eot THEN P := defParc; beg := -1 ELSE P := R.elem(Parc); beg := Texts.Pos(R) END
    END ParcBefore;
    PROCEDURE InitDefParc;
    BEGIN
        IF Modules.ThisMod("ParcElems") = NIL THEN HALT(99) END
        (* side effect: body of ParcElems initialises defParc *)
    END InitDefParc;
    (* Screen Metrics *)
    PROCEDURE Tab (dw: INTEGER; VAR dx: INTEGER);    (*P set*)
        (* dw = line width from left margin to caret (in pixels); dx = distance from caret to next tab stop (in pixels) *)
        VAR i, n: INTEGER; w: LONGINT;
    BEGIN
        i := 0; n := P.nofTabs; w := LONG(dw) * Unit + MinTabWidth;
        IF dw < 0 THEN dx := -dw
        ELSE
            WHILE (i < n) & (P.tab[i] < w) DO INC(i) END;
            IF i < n THEN dx := SHORT((P.tab[i] - LONG(dw) * Unit) DIV Unit)
            ELSE dx := StdTabWidth DIV Unit
            END
        END
    END Tab;
    PROCEDURE MeasureSpecial (dw: INTEGER; VAR dx, x, y, w, h: INTEGER);
        (* returns metrics of nextCh (nextCh <= " "); sends prepare message to elements; P, R, nextCh set *)
        VAR e: Texts.Elem; pat: Display.Pattern; msg: DisplayMsg;
    BEGIN
        IF nextCh = " " THEN Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat);
            x := 0; y := 0; w := dx; h := 0
        ELSIF nextCh = TAB THEN Tab(dw, dx); x := 0; y := 0; w := dx; h := 0
        ELSIF R.elem # NIL THEN e := R.elem;
            msg.prepare := TRUE; msg.indent := LONG(dw) * Unit;
            msg.fnt := R.fnt; msg.col := R.col; msg.pos := Texts.Pos(R)-1;
            msg.Y0 := -SHORT(P.dsr DIV Unit);    (*<<< 18-Nov-91*)
            e.handle(e, msg);
            w := SHORT(e.W DIV Unit);
            dx := w; x := 0; y := msg.Y0; h := SHORT(e.H DIV Unit)    (*<<< 18-Nov-91*)
        ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat)
        END
    END MeasureSpecial;
    PROCEDURE GetSpecial (F: Frame; VAR n: INTEGER; cn, ddx, dw: INTEGER; VAR dx, x, y, w, h: INTEGER);
        (* returns metrics of nextCh (nextCh <= " "); no prepare message to elements; extends blanks for block adjust *)
        (* cn ... add 1 pixel to first cn blanks (block adjust); ddx ... add ddx pixels to every blank (block adjust) *)
        (*P, R, nextCh set*)
        VAR e: Texts.Elem; pat: Display.Pattern;
    BEGIN
        IF nextCh = " " THEN Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat);
            x := 0; y := 0; INC(dx, ddx); INC(n); IF n <= cn THEN INC(dx) END;    (*space correction for block adjustment*)
            w := dx; h := 0
        ELSIF nextCh = TAB THEN Tab(dw, dx); x := 0; y := 0; w := dx; h := 0
        ELSIF R.elem # NIL THEN e := R.elem;
            IF (e IS Parc) & (P.W = 9999 * Unit) THEN (* P gets this value in prepare message *)
                w := Min(SHORT((P.width + P.left) DIV Unit), F.W - F.right - F.left);
                e.W := LONG(w) * Unit
            ELSE w := SHORT(e.W DIV Unit)
            END;
            dx := w; x := 0; y := -SHORT(P.dsr DIV Unit); h := SHORT(e.H DIV Unit)
        ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat)
        END
    END GetSpecial;
    PROCEDURE NextLine (T: Texts.Text; VAR org: LONGINT);    (*R, nextCh set; org = Texts.Pos(R)-1*)
        VAR pat: Display.Pattern; pos, bk, d: LONGINT; width, tw, dx, x, y, w, h: INTEGER;
            R1: Texts.Reader; peekCh: CHAR; indent: INTEGER;
    BEGIN
        tw := 0; dx := 0; w := 0; bk := -999;    (* bk = pos of last seperator *)
        pos := org; ParcBefore(T, pos, P, pbeg); width := SHORT(P.width DIV Unit);
        indent := 0;
        IF org > 0 THEN Texts.OpenReader(R1, T, org - 1); Texts.Read(R1, peekCh);
            IF (peekCh = CR) OR (R1.elem # NIL) & (R1.elem IS Parc) THEN indent := SHORT(P.first DIV Unit) END;
        END;
        INC(tw, indent);
        LOOP INC(pos);    (*inv pos = Texts.Pos(R), ~R.eof => nextCh = text[pos-1]*)
            IF R.eot OR (nextCh = CR) THEN EXIT END;
            INC(tw, dx);
            IF nextCh <= " " THEN MeasureSpecial(tw, dx, x, y, w, h)
            ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat)
            END;
            IF tw + x + w > width THEN d := pos - bk;
                IF (d < AdjustSpan) & (nextCh > " ") THEN pos := bk
                ELSIF ((nextCh > " ") OR (nextCh = Texts.ElemChar)) & (pos > org + 1) THEN DEC(pos)
                END;
                Texts.OpenReader(R, T, pos); Texts.Read(R, nextCh);
                EXIT
            END;
            IF (nextCh <= " ") & (nextCh # Texts.ElemChar) THEN bk := pos END;
            Texts.Read(R, nextCh)
        END;
        org := pos
    END NextLine;
    PROCEDURE BegOfLine (T: Texts.Text; VAR pos: LONGINT; adjust: BOOLEAN);
        (* returns origin of line containing pos *)
        VAR p, org: LONGINT;
    BEGIN
        IF pos <= 0 THEN pos := 0
        ELSE
            IF pos <= T.len THEN org := pos ELSE org := T.len END;
            LOOP    (*search backwards for CR*)
                IF org = 0 THEN EXIT END;
                Texts.OpenReader(R, T, org - 1); Texts.Read(R, nextCh);
                IF nextCh = CR THEN EXIT END;
                DEC(org)
            END;
            IF adjust THEN    (*search forward for actual line origin*)
                Texts.OpenReader(R, T, org); Texts.Read(R, nextCh); p := org;
                REPEAT org := p; NextLine(T, p) UNTIL (p > pos) OR R.eot
            END;
            pos := org
        END
    END BegOfLine;
    PROCEDURE AdjustMetrics (F: Frame; t: TextLine; VAR pw, tw, ddx, cn: INTEGER);    (*t.org set*)
        (* pw ... x-coord of first char in line (in pixels); tw ... width of text line; ddx, cn ... see GetSpecial *)
    BEGIN
        P := t.P; pbeg := t.pbeg;
        pw := F.left; tw := t.w; ddx := 0; cn := 0;
        IF t.pbeg # t.org THEN
            INC(pw, SHORT((P.left + t.indent) DIV Unit));
            IF leftAdj IN P.opts THEN
                IF (rightAdj IN P.opts) & (t.nob > 0) THEN
                    tw := SHORT(P.width DIV Unit); ddx := (tw - t.w0) DIV t.nob; cn := (tw - t.w0) MOD t.nob
                END
            ELSIF rightAdj IN P.opts THEN INC(pw, SHORT(P.width DIV Unit) - t.w0)
            ELSE (*center*) INC(pw, (SHORT(P.width DIV Unit) - t.w0) DIV 2)
            END;
            DEC(tw, SHORT(t.indent DIV Unit));
        END
    END AdjustMetrics;
    (* Screen Placement *)
    PROCEDURE DrawSpecial (F: Frame; px, py, x, y: INTEGER);    (*R, nextCh set*)
        VAR e: Texts.Elem; pat: Display.Pattern; dx, w, h: INTEGER; msg: DisplayMsg;
    BEGIN
        IF (nextCh = TAB) OR (nextCh = CR) THEN (*skip*)
        ELSIF R.elem # NIL THEN e := R.elem;
            IF ~(e IS Parc) OR F.showsParcs THEN
                msg.prepare := FALSE; msg.fnt := R.fnt; msg.col := R.col; msg.pos := Texts.Pos(R) - 1;
                msg.frame := F; msg.X0 := px + x; msg.Y0 := py + y; msg.elemFrame := NIL;
                e.handle(e, msg);
                IF msg.elemFrame # NIL THEN msg.elemFrame.next := F.dsc; F.dsc := msg.elemFrame END;
            ELSIF pageBreak IN e(Parc).opts THEN (*(e IS Parc) & ~F.showsParcs*)
                Display.ReplPattern(Display.white, Display.grey1, px + x, py, SHORT(e.W DIV Unit), 1, Display.replace)
            END
        ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat);
            Display.CopyPattern(R.col, pat, px + x, py + y, Display.invert)
        END;
    END DrawSpecial;
    PROCEDURE ShowLine (F: Frame; t: TextLine; left, right, py: INTEGER);
        VAR pat: Display.Pattern; i: LONGINT; n, cn, lm, px, pw, tw, ddx, dx, x, y, w, h: INTEGER;
    BEGIN
        (* lm ... left parc margin in screen coord; pw ...  x of first char in frame coord *)
        Texts.OpenReader(R, F.text, t.org); AdjustMetrics(F, t, pw, tw, ddx, cn);
        lm := F.X + F.left + SHORT(P.left DIV Unit); px := F.X + pw; INC(py, t.dsr); i := 0; n := 0;
        WHILE i < t.len DO Texts.Read(R, nextCh);
            IF nextCh <= " " THEN GetSpecial(F, n, cn, ddx, px - lm, dx, x, y, w, h)
            ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat)
            END;
            INC(y, R.fnt.height * R.voff DIV 64);
            IF px + x + w <= right THEN
                IF px + x >= left THEN
                    IF nextCh <= " " THEN DrawSpecial(F, px, py, x, y)
                    ELSE
                        IF (R.col = Display.white) & ((F.col = Display.black) OR (F.col = Display.white)) THEN
                            Display.CopyPattern(R.col, pat, px + x, py + y, Display.invert)
                        ELSE
                            Display.CopyPattern(R.col, pat, px + x, py + y, Display.paint)
                        END
                    END
                END;
                INC(px, dx); INC(i)
            ELSE i := t.len
            END
        END
    END ShowLine;
    PROCEDURE ShowLines (F: Frame; botH, topH: INTEGER; erase: BOOLEAN);
        VAR t: TextLine; ph: INTEGER;
    BEGIN
        t := F.trailer.next; ph := F.H - F.top;
        WHILE (t # F.trailer) & (ph - t.h >= topH) DO DEC(ph, t.h); t := t.next END;
        WHILE (t # F.trailer) & (ph - t.h >= botH) DO DEC(ph, t.h);
            IF erase THEN Erase(F, F.X + F.left, F.Y + ph, F.W - F.right - F.left, t.h) END;
            ShowLine(F, t, F.X + F.left, F.X + F.W - F.right, F.Y + ph); t := t.next
        END
    END ShowLines;
    (* Screen Casting *)
    PROCEDURE MeasureLine (F: Frame; maxW: INTEGER; t: TextLine);    (* R, nextCh set *)
        VAR pat: Display.Pattern; len, bklen, d: LONGINT; eol: BOOLEAN;
            nob, bknob, width, minY, bkminY, maxY, bkmaxY, tw, bktw, lsp, dsr, dx, x, y, w, h: INTEGER;
            R1: Texts.Reader; peekCh: CHAR;
            (* bk* ... backup for last blank *)
    BEGIN
        len := 0; nob := 0; bklen := -999; tw := 0; dx := 0; minY := 0; maxY := 0;
        ParcBefore(F.text, t.org, P, pbeg);
        lsp := SHORT(P.lsp DIV Unit); dsr := SHORT(P.dsr DIV Unit); width := SHORT(P.width DIV Unit);
        t.indent := 0;
        IF t.org > 0 THEN Texts.OpenReader(R1, F.text, t.org - 1); Texts.Read(R1, peekCh);
            IF (peekCh = CR) OR (R1.elem # NIL) & (R1.elem IS Parc) THEN t.indent := P.first END;
        END;
        INC(tw, SHORT(t.indent DIV Unit));
        LOOP
            IF R.eot OR (nextCh = CR) THEN nob := 0; eol := ~R.eot; EXIT END;
            IF nextCh <= " " THEN MeasureSpecial(tw, dx, x, y, w, h)
            ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat)
            END;
            IF tw + x + w > width THEN d := len - bklen;
                IF (d < AdjustSpan) & (nextCh > " ") THEN eol := TRUE;
                    Texts.OpenReader(R, F.text, Texts.Pos(R) - d);
                    nob := bknob; len := bklen; tw := bktw; minY := bkminY; maxY := bkmaxY
                ELSIF len = 0 THEN    (* force at least one character on each line *)
                    INC(len); INC(y, R.fnt.height * R.voff DIV 64); minY := Min(minY, y); maxY := Max(maxY, y + h);
                    Texts.Read(R, nextCh); eol := FALSE; tw := maxW
                ELSE eol := (nextCh <= " ") & (nextCh # Texts.ElemChar)
                END;
                EXIT
            END;
            IF (nextCh <= " ") & (nextCh # Texts.ElemChar) THEN
                bknob := nob; bklen := len; bktw := tw; bkminY := minY; bkmaxY := maxY;
                IF nextCh = " " THEN INC(nob) END
            END;
            INC(len); INC(tw, dx); INC(y, R.fnt.height * R.voff DIV 64);
            IF y < minY THEN minY := y END;
            IF y + h > maxY THEN maxY := y + h END;
            Texts.Read(R, nextCh)
        END;
        IF ~F.showsParcs & (pbeg = t.org) THEN dsr := 0; t.h := SHORT(P.lead DIV Unit) + 1
        ELSIF gridAdj IN P.opts THEN
            WHILE dsr < -minY DO INC(dsr, lsp) END;
            t.h := Max(lsp, dsr + maxY); INC(t.h, (-t.h) MOD lsp)
        ELSE dsr := Max(dsr, -minY); t.h := Max(lsp, dsr + maxY)
        END;
        t.len := len; t.w0 := tw; t.w := Min(tw, maxW); t.dsr := dsr; t.nob := nob; t.eot := R.eot; t.P := P; t.pbeg := pbeg;
        IF eol THEN Texts.Read(R, nextCh); t.span := len + 1 ELSE t.span := len END
    END MeasureLine;
    PROCEDURE MeasureLines (F: Frame; org: LONGINT; VAR trailer: TextLine);
        VAR s, t: TextLine; ph: INTEGER;
    BEGIN
        NEW(trailer); s := trailer;
        Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh); ph := F.H - F.top;
        LOOP NEW(t); t.org := org; MeasureLine(F, F.W - F.left - F.right, t);
            IF ph - t.h < F.bot THEN EXIT END;
            s.next := t; s := t; INC(org, s.span); DEC(ph, s.h);
            IF R.eot THEN EXIT END
        END;
        s.next := trailer; trailer.eot := TRUE; trailer.org := org; (* start of first invisible line *) trailer.len := 0; trailer.w := 0;
        trailer.h := SHORT(defParc.lsp DIV Unit); trailer.P := P (* P set by MeasureLine *) ; trailer.pbeg := pbeg
    END MeasureLines;
    (** Locators **)
    PROCEDURE LocateLineTop (F: Frame; trailer: TextLine; org: LONGINT; VAR loc: Location);
        VAR t: TextLine; ph: INTEGER;
    BEGIN
        ph := F.H - F.top; t := trailer.next;
        WHILE (t # trailer) & (t.org # org) DO DEC(ph, t.h); t := t.next END;
        loc.org := org; loc.line := t; loc.y := F.Y + ph
    END LocateLineTop;
    PROCEDURE Width (F: Frame; t: TextLine; pos: LONGINT; VAR pw, dx, dy: INTEGER);
        VAR pat: Display.Pattern; i: LONGINT; n, mw, lm, tw, ddx, cn, x, y, w, h: INTEGER;
    BEGIN
        AdjustMetrics(F, t, pw, tw, ddx, cn); dy := 0; lm := F.left + SHORT(P.left DIV Unit);
        IF t # F.trailer THEN Texts.OpenReader(R, F.text, t.org); Texts.Read(R, nextCh);
            i := 0; n := 0; DEC(pos, t.org); dx := 0; mw := F.W - F.right;
            WHILE ~R.eot & (i < t.len) & (i <= pos) & (pw + dx <= mw) DO
                (* i ... pos of nextCh; dx ... width of char before nextCh; pw ... line width up to pos (or up to right margin) *)
                INC(i); INC(pw, dx);
                IF nextCh <= " " THEN GetSpecial(F, n, cn, ddx, pw - lm, dx, x, y, w, h)
                ELSE Display.GetChar(R.fnt.raster, nextCh, dx, x, y, w, h, pat)
                END;
                dy := R.fnt.height * R.voff DIV 64;
                Texts.Read(R, nextCh)
            END;
            IF (i <= pos) & (pw + dx <= mw) THEN INC(i); INC(pw, dx) END
        ELSE dx := 4
        END
    END Width;
    PROCEDURE LocatePos* (F: Frame; pos: LONGINT; VAR loc: Location);    (* loc.dx = dx of char at pos *)
        VAR t: TextLine; pw, dx, dy: INTEGER;
    BEGIN
        IF pos < F.org THEN pos := F.org; t := F.trailer.next
        ELSIF pos < F.trailer.org THEN t := F.trailer;
            WHILE (t.next # F.trailer) & (t.next.org <= pos) DO t := t.next END
        ELSE pos := F.trailer.org; t := F.trailer.next;
            WHILE ~t.eot DO t := t.next END
        END;
        Width(F, t, pos, pw, dx, dy); LocateLineTop(F, F.trailer, t.org, loc); DEC(loc.y, loc.line.h);
        loc.org := t.org; loc.pos := pos; loc.x := F.X + pw; loc.dx := dx; loc.dy := dy; loc.line := t
    END LocatePos;
    PROCEDURE LocateLine* (F: Frame; y: INTEGER; VAR loc: Location);
        (* loc.x = line start; loc.y = line bottom; loc.dx = line width *)
        VAR t: TextLine; h, ph, pw, tw, ddx, cn: INTEGER;
    BEGIN
        t := F.trailer.next; h := y - F.Y; ph := F.H - F.top - t.h;
        WHILE ~t.eot & (ph - t.next.h >= F.bot) & (ph > h) DO t := t.next; DEC(ph, t.h) END;
        AdjustMetrics(F, t, pw, tw, ddx, cn);
        IF pw >= F.W - F.right THEN pw := F.W - F.right - 4 END;
        loc.org := t.org; loc.pos := loc.org; loc.x := F.X + pw; loc.y := F.Y + ph; loc.dx := tw; loc.dy := 0; loc.line := t
    END LocateLine;
    PROCEDURE LocateChar* (F: Frame; x, y: INTEGER; VAR loc: Location);
        VAR t: TextLine; pat: Display.Pattern; i: LONGINT; n, w, lm, pw, tw, ddx, cn, dx, xc, yc, wc, hc: INTEGER;
    BEGIN
        LocateLine(F, y, loc); t := loc.line; w := x - F.X; AdjustMetrics(F, t, pw, tw, ddx, cn);
        lm := F.left + SHORT(P.left DIV Unit);
        IF (t # F.trailer) & (w > pw) THEN Texts.OpenReader(R, F.text, t.org);
            i := 0; n := 0; dx := 0; nextCh := 0X;
            WHILE (i < t.len) & (pw + dx < w) DO
                (* i = pos after nextCh; dx = width of nextCh; pw = line width without nextCh *)
                Texts.Read(R, nextCh); INC(i); INC(pw, dx);
                IF nextCh <= " " THEN GetSpecial(F, n, cn, ddx, pw - lm, dx, xc, yc, wc, hc)
                ELSE Display.GetChar(R.fnt.raster, nextCh, dx, xc, yc, wc, hc, pat)
                END
            END;
            IF pw + dx < w THEN INC(i); INC(pw, dx); R.elem := NIL END;
            INC(loc.pos, i - 1); loc.x := F.X + pw;
            IF i < t.len THEN loc.dx := dx; loc.dy := R.fnt.height * R.voff DIV 64 ELSE loc.dx := 4 END
        ELSE loc.dx := 4; R.elem := NIL
        END
    END LocateChar;
    PROCEDURE LocateWord* (F: Frame; x, y: INTEGER; VAR loc: Location);
        VAR t: TextLine; pos, i: LONGINT; px, rx: INTEGER; pat: Display.Pattern; dx, xc, yc, wc, hc: INTEGER;
    BEGIN
        LocateChar(F, x, y, loc); pos := loc.pos + 1;
        REPEAT DEC(pos); Texts.OpenReader(R, F.text, pos); Texts.Read(R, nextCh)
        UNTIL (pos < loc.org) OR (nextCh > " ");
        INC(pos);
        REPEAT DEC(pos); Texts.OpenReader(R, F.text, pos); Texts.Read(R, nextCh)
        UNTIL (pos < loc.org) OR (nextCh <= " ");
        LocatePos(F, pos + 1, loc); t := loc.line; i := loc.pos - loc.org;
        IF i < t.len THEN px := loc.x; rx := F.X + F.W - F.right;
            Texts.OpenReader(R, F.text, loc.pos); dx := 0; wc := 0; nextCh := "x";
            WHILE (i < t.len) & (nextCh > " ") & (px + dx < rx) DO
                Texts.Read(R, nextCh); INC(i); INC(px, dx);
                Display.GetChar(R.fnt.raster, nextCh, dx, xc, yc, wc, hc, pat)
            END;
            IF (nextCh > " ") & (px + dx < rx) THEN INC(i); INC(px, dx) END;
            loc.dx := px - loc.x
        ELSE loc.dx := 0
        END
    END LocateWord;
    PROCEDURE Pos* (F: Frame; x, y: INTEGER): LONGINT;
        VAR loc: Location;
    BEGIN LocateChar(F, x, y, loc); RETURN loc.pos
    END Pos;
    PROCEDURE WordBeg (t: Texts.Text; pos: LONGINT): LONGINT;
        VAR r: Texts.Reader; ch: CHAR; pos0: LONGINT;
    BEGIN
        pos0 := pos; Texts.OpenReader(r, t, pos); Texts.Read(r, ch);
        WHILE (CAP(ch) >= "A") & (CAP(ch) <= "Z") OR (ch >= "0") & (ch <= "9") DO
            DEC(pos); IF pos < 0 THEN RETURN 0 END;
            Texts.OpenReader(r, t, pos); Texts.Read(r, ch)
        END;
        IF pos < pos0 THEN INC(pos) END;
        RETURN pos
    END WordBeg;
    PROCEDURE WordEnd (t: Texts.Text; pos: LONGINT): LONGINT;
        VAR r: Texts.Reader; ch: CHAR; pos0: LONGINT;
    BEGIN
        pos0 := pos; Texts.OpenReader(r, t, pos); Texts.Read(r, ch);
        WHILE (CAP(ch) >= "A") & (CAP(ch) <= "Z") OR (ch >= "0") & (ch <= "9") DO
            INC(pos); Texts.Read(r, ch)
        END;
        IF pos = pos0 THEN INC(pos) END;
        RETURN pos
    END WordEnd;
    PROCEDURE ThisSubFrame (F: Frame; x, y: INTEGER): Display.Frame;
        VAR f: Display.Frame;
    BEGIN f := F.dsc;
        WHILE (f # NIL) & ((x < f.X) OR (x >= f.X + f.W) OR (y < f.Y) OR (y >= f.Y + f.H)) DO f := f.next END;
        RETURN f
    END ThisSubFrame;
    (** Caret & Selection **)
    PROCEDURE PassSubFocus (F: Frame; f: Display.Frame);
        (* pass focus from F.focus to f (f is also an element frame in F) *)
        VAR loc: Location; f1: Display.Frame; ctrl: Oberon.ControlMsg; focus: FocusMsg;
    BEGIN
        IF F.focus # NIL THEN f1 := F.focus;
            ctrl.id := Oberon.defocus; f1.handle(f1, ctrl);
            LocateChar(F, f1.X + 1, f1.Y + 1, loc);
            InvertBorder(f1); F.focus := NIL;
            IF R.elem # NIL THEN
                focus.focus := FALSE; focus.elemFrame := f1; focus.frame := F; R.elem.handle(R.elem, focus)
            END
        END;
        IF f # NIL THEN
            LocateChar(F, f.X + 1, f.Y + 1, loc);    (* side effect: set R to element *)
            focus.focus := TRUE; focus.elemFrame := f; focus.frame := F; R.elem.handle(R.elem, focus);
            InvertBorder(f)
        END;
        F.focus := f
    END PassSubFocus;
    PROCEDURE RemoveSelection* (F: Frame);
    BEGIN
        IF F.hasSel THEN InvertSelection(F, F.selbeg, F.selend); F.hasSel := FALSE END
    END RemoveSelection;
    PROCEDURE SetSelection* (F: Frame; beg, end: LONGINT);    (** forces range to visible bounds **)
        VAR loc: Location;
    BEGIN
        IF end > F.text.len THEN end := F.text.len END;
        IF end > beg THEN
            IF F.hasSel & (F.selbeg.pos = beg) THEN
                IF (F.selend.pos < end) & (F.selend.pos < F.trailer.org) THEN
                    LocatePos(F, F.selend.pos, loc); LocatePos(F, end, F.selend); InvertSelection(F, loc, F.selend)
                ELSIF end < F.selend.pos THEN
                    LocatePos(F, end, loc); InvertSelection(F, loc, F.selend); LocatePos(F, end, F.selend)
                END
            ELSE RemoveSelection(F); PassSubFocus(F, NIL);
                LocatePos(F, beg, F.selbeg); LocatePos(F, end, F.selend); InvertSelection(F, F.selbeg, F.selend)
            END;
            F.hasSel := TRUE; F.time := Oberon.Time()
        END
    END SetSelection;
    PROCEDURE RemoveCaret* (F: Frame);
        VAR msg: Oberon.ControlMsg;
    BEGIN
        IF F.focus # NIL THEN msg.id := Oberon.defocus; F.focus.handle(F.focus, msg) END;
        IF F.hasCar THEN InvertCaret(F); F.hasCar := FALSE END
    END RemoveCaret;
    PROCEDURE SetCaret* (F: Frame; pos: LONGINT);    (** only done if within visible bounds **)
    BEGIN
        IF ~F.hasCar OR (F.carloc.pos # pos) THEN RemoveCaret(F); PassSubFocus(F, NIL);
            LocatePos(F, pos, F.carloc);
            IF F.carloc.x <= F.X + F.W - F.right THEN InvertCaret(F); F.hasCar := TRUE END
        END
    END SetCaret;
    (** Display Range **)
    PROCEDURE Complete (F: Frame; trailer: TextLine; s: TextLine; org: LONGINT; ph: INTEGER);
        VAR u: TextLine;
    BEGIN
        IF ph > F.bot THEN    (*try to add new lines to the bottom*)
            Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh);
            LOOP
                IF R.eot THEN EXIT END;
                NEW(u); u.org := org; MeasureLine(F, F.W - F.left - F.right, u);
                IF ph - u.h < F.bot THEN EXIT END;
                s.next := u; s := s.next; DEC(ph, s.h); INC(org, s.span)
            END
        END;
        s.next := trailer; trailer.eot := TRUE; trailer.org := org; trailer.len := 0; trailer.w := 0;
        trailer.h := SHORT(defParc.lsp DIV Unit); trailer.P := P; trailer.pbeg := pbeg
    END Complete;
    PROCEDURE ShowFrom (F: Frame; pos: LONGINT);    (* removes global marks as needed and neutralizes F *)
        VAR new, s: TextLine; beg, end: Location; org: LONGINT; ph, y0, dy: INTEGER;
    BEGIN
        F.handle(F, neutralize);
        IF (F.trailer # NIL) & (F.org < pos) & (pos < F.trailer.org) THEN    (* shift up and extend to the bottom *)
            LocateLineTop(F, F.trailer, pos, beg); LocateLineTop(F, F.trailer, F.trailer.org, end);
            dy := (F.Y + F.H - F.top) - beg.y; Shift(F, end.y, end.y + dy, beg.y - end.y);
            Erase(F, F.X + F.left, end.y, F.W - F.left, dy);
            s := F.trailer.next; WHILE s.org # pos DO s := s.next END;
            F.trailer.next := s; org := s.org + s.span; ph := F.H - F.top - s.h;
            WHILE s.next # F.trailer DO s := s.next; org := org + s.span; ph := ph - s.h END;
            Complete(F, F.trailer, s, org, ph); F.org := pos; ShowLines(F, F.bot, end.y + dy - F.Y, FALSE)
        ELSIF (F.trailer = NIL) OR (pos # F.org) THEN
            MeasureLines(F, pos, new);
            IF (F.trailer # NIL) & (pos < F.org) & (F.org <= new.org) THEN    (* shift down and extend to the top *)
                LocateLineTop(F, new, F.org, beg); LocateLineTop(F, new, new.org, end);
                y0 := F.Y + F.H - F.top; Shift(F, y0 - (beg.y - end.y), end.y, beg.y - end.y);
                Erase(F, F.X + F.left, beg.y, F.W - F.left, y0 - beg.y);
                Erase(F, F.X + F.left, F.Y + F.bot, F.W - F.left, end.y - (F.Y + F.bot));
                F.org := pos; F.trailer := new; ShowLines(F, beg.y - F.Y, F.H - F.top, FALSE)
            ELSE    (* full redisplay *)
                IF F.trailer = NIL THEN Erase(F, F.X, F.Y, F.W, F.H); ShowBar(F, 0, F.H); F.markH := -1
                ELSE Erase(F, F.X + F.left, F.Y + F.bot, F.W - F.left, F.H - F.bot - F.top)
                END;
                F.org := pos; F.trailer := new; ShowLines(F, F.bot, F.H - F.top, FALSE)
            END
        END;
        ShowTick(F)
    END ShowFrom;
    PROCEDURE Show* (F: Frame; pos: LONGINT);    (** removes global marks as needed and neutralizes F **)
    BEGIN BegOfLine(F.text, pos, TRUE); ShowFrom(F, pos)
    END Show;
    PROCEDURE Resize (F: Frame; x, y, w, h: INTEGER);
        VAR oldY, oldH, dh, ph: INTEGER; t: TextLine;
    BEGIN
        IF (w = 0) OR (h = 0) THEN InvalSubFrames(F, F.X, F.Y, F.W, F.H);
            F.X := x; F.Y := y; F.W := w; F.H := h; F.trailer := NIL
        ELSIF (F.trailer # NIL) & (x = F.X) & (w = F.W) THEN
            oldY := F.Y; oldH := F.H; F.markH := -1; F.Y := y; F.H := h;
            IF h > oldH THEN dh := h - oldH;    (* extend *)
                IF y + h # oldY + oldH THEN
                    Display.CopyBlock(x+F.barW, oldY, w-F.barW, oldH, x+F.barW, y + dh, Display.replace);    (*CM 08.08.94*)
                    ShiftSubFrames(F, oldY, y + dh, oldH)
                END;
                EraseRect(F, x, y, w, dh);                                                                                                (*CM 08.08.94*)
                t := F.trailer; ph := F.H - F.top;
                WHILE t.next # F.trailer DO t := t.next; ph := ph - t.h END;
                Complete(F, F.trailer, t, F.trailer.org, ph); ShowLines(F, F.bot, ph, FALSE)
            ELSE dh := oldH - h;    (* reduce *)
                IF y + h # oldY + oldH THEN
                    Display.CopyBlock(x+F.barW, oldY + dh, w-F.barW, h, x+F.barW, y, Display.replace);    (*CM 08.08.94*)
                    ShiftSubFrames(F, oldY + dh, y, h)
                END;
                t := F.trailer; ph := F.H - F.top;
                WHILE (t.next # F.trailer) & (ph - t.next.h >= F.bot) DO t := t.next; DEC(ph, t.h) END;
                IF t = F.trailer THEN t.org := F.org; t.span := 0 END;
                Complete(F, F.trailer, t, t.org + t.span, ph);
                EraseRect(F, x + F.left, y, w - F.left, ph);
                InvalSubFrames(F, x, oldY, w, y - oldY); InvalSubFrames(F, x, y + h, w, dh - (y - oldY))
            END;
            ShowBar(F,0,h);                                                                                                        (*CM 08.08.94*)
            ShowTick(F)
        ELSE F.X := x; F.Y := y; F.W := w; F.H := h; F.trailer := NIL; Show(F, F.org); ShowBar(F,0,h)
        END
    END Resize;
    (** Contents Update **)
    PROCEDURE Update (F: Frame; VAR msg: UpdateMsg);    (** removes global marks as needed **)
        VAR t: TextLine; org, d: LONGINT;
        PROCEDURE Begin (VAR beg: LONGINT; VAR org0: LONGINT; VAR q: TextLine);
            (* org0 = origin of first affected line; beg = pos of first modified character; q = first affected line (if line origin has not moved).*)
            (* q = NIL => beg = org0; q # NIL => first (beg-org0) characters of q need not be redrawn *)
            VAR trailer, t: TextLine;
        BEGIN
            trailer := F.trailer; t := trailer; q := NIL;
            WHILE (t.next # trailer) & (beg >= t.next.org + t.next.span) & ~t.next.eot DO t := t.next END;
            q := t.next; org0 := beg; BegOfLine(F.text, org0, TRUE);
            IF (org0 # q.org) OR (q = trailer) THEN
                IF org0 > q.org THEN org0 := q.org END;
                beg := org0; q := NIL
            END
        END Begin;
        PROCEDURE Adjust (end, delta: LONGINT);
            (* H1 = top of synchronization line in old frame *)
            (* h0 = top of line that was modified *)
            (* h1 = top of block in new frame that could be reused *)
            (* h2 = bottom of last line in new frame *)
            (* h1 - h2 = height of block that could be reused *)
            VAR new, old, s, t, u, p, q: TextLine; bot: Location;
                org, org0, beg: LONGINT; ph, h0, h1, H1, h2, lm, dx, dy: INTEGER;
        BEGIN
            q := NIL; LocateLineTop(F, F.trailer, F.trailer.org, bot);
            IF msg.beg < F.org THEN org0 := F.org; beg := org0 ELSE beg := msg.beg; Begin(beg, org0, q) END;
            NEW(new); s := new; old := F.trailer; t := old; org := F.org; ph := F.H - F.top;
            WHILE (t.next # old) & (t.next.org # org0) DO t := t.next;    (*transfer unchanged prefix*)
                s.next := t; s := t; DEC(ph, s.h); INC(org, s.span)
            END;
            h0 := ph; H1 := h0; t := t.next; p := s;
            Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh);    (*rebuild at least one line descriptor*)
            LOOP NEW(u); u.org := org; MeasureLine(F, F.W - F.left - F.right, u);
                IF ph - u.h < F.bot THEN h1 := ph; h2 := h1; EXIT END;
                s.next := u; s := s.next; DEC(ph, s.h); INC(org, s.span);
                IF R.eot THEN h1 := ph; h2 := h1; EXIT END;
                IF org > end THEN
                    WHILE (t # old) & (org > t.org + delta) DO DEC(H1, t.h); t := t.next END;
                    IF (org = t.org + delta) & (P = t.P) THEN h1 := ph;    (*resynchronized*)
                        WHILE (t # old) & (ph - t.h >= F.bot) DO    (*transfer unchanged suffix*)
                            s.next := t; s := t; s.org := org; ParcBefore(F.text, s.org, s.P, s.pbeg);
                            DEC(ph, s.h); INC(org, s.span); t := t.next
                        END;
                        h2 := ph; EXIT
                    END
                END
            END;
            Shift(F, F.Y + H1 - (h1 - h2), F.Y + h2, h1 - h2);
            Complete(F, new, s, org, ph); F.trailer := new; t := p.next;
            IF (q # NIL) & (q.h = t.h) & (q.dsr = t.dsr) & (q.org = t.org) & (q.P = t.P) & (end <= t.org + t.span) THEN
                P := t.P; pbeg := t.pbeg;
                IF (P.opts * AdjMask = {leftAdj}) OR (P.opts * AdjMask = AdjMask) & (q.nob = 0) & (t.nob = 0) THEN
                    Width(F, t, beg, lm, dx, dy);    (*preserve prefix of first affected line*)
                    DEC(h0, t.h); Erase(F, F.X + lm, F.Y + h0, F.W - lm, t.h);
                    ShowLine(F, t, F.X + lm, F.X + F.W - F.right, F.Y + h0)
                END
            END;
            ShowLines(F, h1, h0, TRUE);
            Erase(F, F.X + F.left, bot.y, F.W - F.left, h2 - (bot.y - F.Y)); ShowLines(F, F.bot, h2, FALSE)
        END Adjust;
    BEGIN F.handle(F, neutralize); MarkMenu(F);
        IF (msg.id = Texts.insert) & (msg.beg < F.org) THEN t := F.trailer; d := msg.end - msg.beg; INC(F.org, d);
            REPEAT INC(t.org, d); t := t.next UNTIL t = F.trailer
        ELSIF (msg.id = Texts.delete) & (msg.end <= F.org) THEN t := F.trailer; d := msg.end - msg.beg; DEC(F.org, d);
            REPEAT DEC(t.org, d); t := t.next UNTIL t = F.trailer
        END;
        org := F.org;
        IF msg.beg <= F.org + AdjustSpan THEN BegOfLine(F.text, org, TRUE) END;
        ParcBefore(F.text, org, P, d);
        IF (org # F.org) OR (P # F.trailer.next.P) THEN
            F.trailer := NIL; Show(F, F.org)
        ELSIF (msg.end > org) & (msg.beg < F.trailer.org + AdjustSpan) THEN
            IF msg.id = Texts.replace THEN Adjust(msg.end, 0)
            ELSIF msg.id = Texts.insert THEN Adjust(msg.end, msg.end - msg.beg)
            ELSIF msg.id = Texts.delete THEN Adjust(msg.beg, msg.beg - msg.end)
            END
        END;
        ShowTick(F)
    END Update;
    (** User Interface **)
    PROCEDURE Back (F: Frame; dY: INTEGER; (*inout*) VAR org: LONGINT);    (* mh 10.10.92 *)
        (* computes new org such that old org is (at most) dY pixels below new org *)
        VAR H: INTEGER; oldOrg: LONGINT;
        PROCEDURE TotalHeight (org1, org2: LONGINT): INTEGER;
            (* measures total height of text-lines starting at org1 and ending at the line before the line containing org2 *)
            VAR h: INTEGER; line: TextLine;
        BEGIN
            Texts.OpenReader(R, F.text, org1); Texts.Read(R, nextCh); NEW(line); h := 0;
            LOOP line.org := org1;
                MeasureLine(F, F.W - F.left - F.right, line); INC(org1, line.span);
                IF Texts.Pos(R)-1 > org2 THEN EXIT END;
                INC(h, line.h);
                IF R.eot THEN EXIT END;
            END;
            RETURN h
        END TotalHeight;
        PROCEDURE Forward (h: INTEGER);
            (* increase org by n text-lines such that the sum of the n line-heights > h *)
            VAR line: TextLine;
        BEGIN
            Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh); NEW(line);
            WHILE h > 0 DO line.org := org;
                MeasureLine(F, F.W - F.left - F.right, line); INC(org, line.span); DEC(h, line.h);
            END;
            org := Texts.Pos(R)-1;
        END Forward;
    BEGIN H := 0;
        LOOP oldOrg := org;
            IF org = 0 THEN EXIT END;
            DEC(org, 800); BegOfLine(F.text, org, FALSE);
            INC(H, TotalHeight(org, oldOrg));
            IF H > dY THEN EXIT END;
        END;
        Forward(H - dY);
    END Back;
    PROCEDURE TrackLine* (F: Frame; VAR x, y: INTEGER; VAR org: LONGINT; VAR keysum: SET);
        VAR keys: SET; new, old: Location;
    BEGIN
        LocateLine(F, y, old); InvertRect(F, old.x, old.y, old.dx + 4, 2); keysum := {};
        REPEAT TrackMouse(x, y, keys, keysum); LocateLine(F, y, new);
            IF new.org # old.org THEN
                InvertRect(F, new.x, new.y, new.dx + 4, 2); InvertRect(F, old.x, old.y, old.dx + 4, 2); old := new
            END
        UNTIL keys = {};
        InvertRect(F, new.x, new.y, new.dx + 4, 2); org := new.org
    END TrackLine;
    PROCEDURE TrackWord* (F: Frame; VAR x, y: INTEGER; VAR pos: LONGINT; VAR keysum: SET);
        VAR keys: SET; new, old: Location;
    BEGIN
        LocateWord(F, x, y, old); InvertRect(F, old.x, old.y, old.dx, 2); keysum := {};
        REPEAT TrackMouse(x, y, keys, keysum); LocateWord(F, x, y, new);
            IF new.pos # old.pos THEN
                InvertRect(F, new.x, new.y, new.dx, 2); InvertRect(F, old.x, old.y, old.dx, 2); old := new
            END
        UNTIL keys = {};
        InvertRect(F, new.x, new.y, new.dx, 2); pos := new.pos
    END TrackWord;
    PROCEDURE TrackCaret* (F: Frame; VAR x, y: INTEGER; VAR keysum: SET);
        VAR keys: SET;
    BEGIN keysum := {};
        REPEAT TrackMouse(x, y, keys, keysum); SetCaret(F, Pos(F, x, y)) UNTIL keys = {}
    END TrackCaret;
    PROCEDURE TrackSelection* (F: Frame; VAR x, y: INTEGER; VAR keysum: SET);
        VAR keys: SET; pos, pos0, beg, end: LONGINT; V: Viewers.Viewer; f: Frame; loc: Location;
    BEGIN
        IF F.hasSel THEN beg := F.selbeg.pos; end := F.selend.pos
        ELSE beg := Pos(F, x, y); end := beg + 1; SetSelection(F, beg, end)
        END;
        V := Viewers.This(F.X, F.Y); V := V.next(Viewers.Viewer);
        IF (V.dsc # NIL) & (V.dsc.next # NIL) & (V.dsc.next IS Frame) THEN f := V.dsc.next(Frame);
            IF f.hasSel & (f.text = F.text) THEN
                IF (f.selbeg.pos < f.trailer.org) & (f.org < f.selend.pos) & (f.selbeg.pos <= Pos(F, x, y)) THEN
                    beg := f.selbeg.pos; SetSelection(F, beg, end)
                ELSE RemoveSelection(f); f := NIL
                END
            ELSE f := NIL
            END
        ELSE f := NIL
        END;
        keysum := keysum - {0..2}; pos0 := beg;
        REPEAT
            TrackMouse(x, y, keys, keysum); pos := Pos(F, x, y);
            IF pos < pos0 THEN end := pos0;
                IF trackLine IN keysum THEN LocateLine(F, y, loc); beg := loc.org
                ELSIF trackWord IN keysum THEN beg := WordBeg(F.text, pos)
                ELSE beg := pos
                END
            ELSE beg := pos0;
                IF trackLine IN keysum THEN LocateLine(F, y, loc); end := loc.org + loc.line.span
                ELSIF trackWord IN keysum THEN end := WordEnd(F.text, pos)
                ELSE end := pos + 1
                END
            END;
            IF beg >= F.org THEN SetSelection(F, beg, end) ELSE SetSelection(F, F.org, end) END;
            IF f # NIL THEN SetSelection(f, beg, end) END
        UNTIL keys = {};
        IF f # NIL THEN F.selbeg.pos := beg END
    END TrackSelection;
    PROCEDURE Call (F: Frame; pos: LONGINT; new: BOOLEAN);
        VAR S: Texts.Scanner; res, i, j: INTEGER;
    BEGIN
        Texts.OpenScanner(S, F.text, pos); Texts.Scan(S);
        IF (S.class = Texts.Name) & (S.line = 0) THEN
            i := 0; WHILE (i < S.len) & (S.s[i] # ".") DO INC(i) END;
            j := i + 1; WHILE (j < S.len) & (S.s[j] # ".") DO INC(j) END;
            IF (j >= S.len) & (S.s[i] = ".") THEN
                par.vwr := Viewers.This(F.X, F.Y);
                par.frame := F; par.text := F.text; par.pos := pos + S.len;
                Oberon.Call(S.s, par, new, res);
                IF res > 0 THEN
                    Texts.WriteString(W0, "Call error: "); Texts.WriteString(W0, Modules.importing);    (* mf *)
                    IF res=1 THEN Texts.WriteString(W0, " not found")
                    ELSIF res=2 THEN Texts.WriteString(W0, " not a valid object file")
                    ELSIF res=3 THEN Texts.WriteString(W0, " imports "); Texts.WriteString(W0, Modules.imported);
                        Texts.WriteString(W0, " with bad key")
                    ELSIF res=4 THEN Texts.WriteString(W0, " not enough memory")
                    ELSIF res=5 THEN Texts.WriteString(W0, " module not found")
                    ELSIF res=6 THEN
                        IF Modules.importing[0]#CHR(0) THEN Texts.WriteString(W0, " command not found")
                        ELSE Texts.OpenWriter (W0);
                        END
                    ELSE Texts.WriteString(W0, " res = "); Texts.WriteInt(W0, res, 0)
                    END
                ELSIF res < 0 THEN
                    IF i + 1 = S.len THEN Texts.OpenWriter(W0); res := 0  (*execution of module body*)
                    ELSE
                        INC(i); WHILE i < S.len DO Texts.Write(W0, S.s[i]); INC(i) END;
                        Texts.WriteString(W0, " not found")
                    END
                END;
                IF res # 0 THEN Texts.WriteLn(W0); Texts.Append(Oberon.Log, W0.buf) END
            END
        END
    END Call;
    PROCEDURE PickAttributes (VAR W: Texts.Writer; ch: CHAR; T: Texts.Text; pos: LONGINT; fnt: Fonts.Font; col, voff: SHORTINT);
        VAR R: Texts.Reader; ch0: CHAR;
    BEGIN
        IF T.len > 0 THEN
            IF pos < T.len THEN Texts.OpenReader(R, T, pos); Texts.Read(R, ch0) END;
            IF (pos > 0) & ((pos = T.len) OR (ch0 <= " ")) THEN
                Texts.OpenReader(R, T, pos - 1); Texts.Read(R, ch0)
            END;
            Texts.SetFont(W, R.fnt); Texts.SetColor(W, R.col);
            IF (ch = CR) OR (ch = TAB)  THEN Texts.SetOffset(W, voff) ELSE Texts.SetOffset(W, R.voff) END
        ELSE Texts.SetFont(W, fnt); Texts.SetColor(W, col); Texts.SetOffset(W, voff)
        END
    END PickAttributes;
    PROCEDURE ShiftBlock (F: Frame; delta: INTEGER);    (* shift selected lines to left or right *)
        VAR text: Texts.Text; pos, beg, end, time: LONGINT; select: SelectMsg; ch: CHAR;
    BEGIN
        Oberon.GetSelection(text, beg, end, time);
        IF (time >= 0) & (text = F.text) THEN BegOfLine(F.text, beg, FALSE); pos := beg;
            WHILE pos < end DO Texts.OpenReader(R, F.text, pos); Texts.Read(R, ch);
                WHILE (R.elem # NIL) & (R.elem IS Parc) & (pos < end) DO Texts.Read(R, ch); INC(pos) END;
                IF pos < end THEN
                    IF delta < 0 THEN
                        IF (ch <= " ") & (ch # CR) & (ch # Texts.ElemChar) THEN
                            Texts.Delete(F.text, pos, pos + 1); DEC(end)
                        END
                    ELSE
                        PickAttributes(W, TAB, text, pos, Oberon.CurFnt, Oberon.CurCol, Oberon.CurOff);
                        IF (ch <= " ") & (ch # CR) & (ch # Texts.ElemChar) THEN Texts.Write(W, ch)    (* first char extension *)
                        ELSE Texts.Write(W, TAB)
                        END;
                        Texts.Insert(F.text, pos, W.buf); INC(end); INC(pos)
                    END;
                    Texts.OpenReader(R, F.text, pos);
                    REPEAT Texts.Read(R, ch) UNTIL R.eot OR (ch = CR);
                    pos := Texts.Pos(R)
                END
            END;
            select.text := F.text; select.beg := beg; select.end := pos; select.time := Oberon.Time();
            Viewers.Broadcast(select)
        END
    END ShiftBlock;
    PROCEDURE Write (F: Frame; ch: CHAR; fnt: Fonts.Font; col, voff: SHORTINT);
        VAR loc: Location; parc: Parc; org, pos, pbeg: LONGINT; i: INTEGER;
            buf: ARRAY 32 OF CHAR; v: Viewers.Viewer; f: Frame;
            copy: Texts.CopyMsg; input: Oberon.InputMsg;
        PROCEDURE Visible(ch: CHAR): BOOLEAN;
            VAR pat: Display.Pattern; dx, x, y, w, h: INTEGER;
        BEGIN Display.GetChar(W.fnt.raster, ch, dx, x, y, w, h, pat); RETURN dx > 0
        END Visible;
        PROCEDURE InsertBuffer;
            VAR i, j: INTEGER; ch: CHAR;
        BEGIN i := 0; j := 0; ch := buf[i];
            WHILE ch # 0X DO
                IF (ch = TAB) OR (ch = CR) OR (ch = " ") OR Visible(ch) THEN Texts.Write(W, ch); INC(j) END;
                INC(i); ch := buf[i]
            END;
            IF j > 0 THEN Texts.Insert(F.text, pos, W.buf); INC(pos, LONG(j)) END
        END InsertBuffer;
        PROCEDURE Flush;
            VAR ch: CHAR;
        BEGIN
            WHILE Input.Available() > 0 DO Input.Read(ch) END
        END Flush;
    BEGIN
        IF F.hasSel THEN
            IF ch = CRSL THEN ShiftBlock(F, -1)
            ELSIF ch = CRSR THEN ShiftBlock(F, 1)
            ELSIF ch < 80X THEN
                pos := F.selbeg.pos; v := Viewers.Next(Viewers.This(F.X, F.Y));
                IF (v.dsc # NIL) & (v.dsc.next # NIL) & (v.dsc.next IS Frame) THEN
                    f := v.dsc.next(Frame);
                    IF (f.text = F.text) & f.hasSel & (f.selbeg.pos < pos) THEN pos := f.selbeg.pos END
                END;
                Texts.Delete(F.text, pos, F.selend.pos); SetCaret(F, pos);
                IF ch # DEL THEN Write(F, ch, fnt, col, voff) END
            END
        ELSIF F.hasCar THEN pos := F.carloc.pos;
            IF ch = DEL THEN
                IF pos > F.org THEN DEC(pos); Texts.Delete(F.text, pos, pos + 1); Flush END
            ELSIF (ch = DELRIGHT) & (pos < F.text.len) THEN Texts.Delete(F.text, pos, pos + 1); Flush        (*<< mah del right *)
            ELSIF ch = HOME THEN pos := Pos (F, F.X, F.carloc.y)                (*<< mah beg of line *)
            ELSIF ch = EOL THEN pos := Pos (F, F.X+F.W-1, F.carloc.y)        (*<< mah end of line *)
            ELSIF (ch = CRSL) & (pos > 0) THEN DEC(pos)
            ELSIF (ch = CRSR) & (pos < F.text.len) THEN INC(pos)
            ELSIF (ch = CRSU) & (pos > 0) THEN                                    (*<< mah cursor up *)
                org:=Pos (F, F.carloc.x+1, F.carloc.y+F.carloc.line.h);
                IF org=pos THEN Show (F, F.org-1) END;
                pos:=Pos (F, F.carloc.x+1, F.carloc.y+F.carloc.line.h)
            ELSIF (ch = CRSD) & (pos < F.text.len) THEN                        (*<< mah cursor down *)
                org:=Pos (F, F.carloc.x+1, F.carloc.y-F.carloc.line.next.h);
                IF (org=pos) & (F.trailer.org+F.trailer.len#F.text.len) THEN Show (F, F.trailer.next.next.org) END;
                LocatePos (F, pos, loc);
                pos:=Pos (F, F.carloc.x+1, loc.y-loc.line.next.h)
            ELSIF ch=PGUP THEN                                                    (*<< mah page up *)
                LocateLine (F, F.Y+F.H-1, loc); i:=loc.y-F.Y-F.bot;
                Back (F, i, pos); Show (F, pos); pos:=F.org
            ELSIF ch=PGDN THEN                                                (*<< mah page down *)
                IF F.trailer.org+F.trailer.len = F.text.len THEN pos:=F.trailer.org
                ELSE LocateLine (F, F.Y, loc); Show (F, loc.org); pos:=F.org
                END
            ELSIF (ch = CRSL) OR (ch = CRSU) OR (ch = CRSD) OR (ch = CRSR) OR (ch = PGUP) OR (ch=PGDN) THEN
            ELSIF (ch = BRK) OR (ch = ShiftBRK) THEN
                ParcBefore(F.text, pos, P, pbeg); P.handle(P, copy); parc := copy.e(Parc);
                IF ch = BRK THEN EXCL(parc.opts, pageBreak) ELSE INCL(parc.opts, pageBreak) END;
                PickAttributes(W, Texts.ElemChar, F.text, pos, fnt, col, voff);
                Texts.WriteElem(W, parc); Texts.Insert(F.text, pos, W.buf); INC(pos)
            ELSIF (ch = TAB) OR (ch = CR) OR (ch >= " ") THEN
                PickAttributes(W, ch, F.text, pos, fnt, col, voff);
                IF ch = CR THEN buf[0] := CR; i := 1; org := F.carloc.org; BegOfLine(F.text, org, FALSE);
                    Texts.OpenReader(R, F.text, org);
                    REPEAT Texts.Read(R, ch) UNTIL (R.elem = NIL) OR ~(R.elem IS Parc);
                    WHILE (Texts.Pos(R) <= pos) & (ch <= " ") & (ch # Texts.ElemChar) & (i < 31) DO
                        buf[i] := ch; INC(i); Texts.Read(R, ch)
                    END
                ELSIF ch = LF THEN buf[0] := CR; i:=1            (*<< mah Enter on numeric pad has no autoindent *)
                ELSE buf[0] := ch; i := 1
                END;
                buf[i] := 0X; InsertBuffer
            END;
            IF pos < F.org THEN Show(F, F.org - 1) END;
            SetCaret(F, pos);
            WHILE F.carloc.y < F.Y + F.bot DO Show(F, F.trailer.next.next.org); Flush; SetCaret(F, pos) END
        ELSIF F.focus # NIL THEN input.id := Oberon.consume; input.ch := ch;
            input.fnt := fnt; input.col := col; input.voff := voff; F.focus.handle(F.focus, input)
        END
    END Write;
    PROCEDURE TouchElem (F: Frame; VAR x, y: INTEGER; VAR keysum: SET);
        VAR loc: Location; e: Texts.Elem; pbeg: LONGINT; y0: INTEGER;
            track: TrackMsg;
    BEGIN
        LocateChar(F, x, y, loc); e := R.elem;
        IF (e # NIL) & (loc.x + e.W DIV Unit <= F.X + F.W - F.right) THEN
            ParcBefore(F.text, loc.pos, P, pbeg); y0 := loc.y + loc.line.dsr - SHORT(P.dsr DIV Unit) + loc.dy;
            IF (loc.x <= x) & (x < loc.x + e.W DIV Unit) & (keysum= {middleKey}) THEN
                track.X := x; track.Y := y; track.keys := keysum;
                track.fnt := R.fnt; track.col := R.col; track.pos := Texts.Pos(R) - 1;
                track.frame := F; track.X0 := loc.x; track.Y0 := y0;
                e.handle(e, track); keysum := {}
            END
        END
    END TouchElem;
    PROCEDURE Edit (F: Frame; x, y: INTEGER; keysum: SET);
        VAR ef: Display.Frame; pos, pos0, i: LONGINT; keys: SET; input: Oberon.InputMsg; loc: Location;
    BEGIN
        IF x < F.X + F.barW THEN
            IF keysum # {} THEN scrollBar.HandleScrollBar(F, x, y, keysum)
            ELSE DrawCursor(x, y)
            END
        ELSE    (* text area *)
            ef := ThisSubFrame(F, x, y);
            IF ef # NIL THEN    (* within sub-frame *)
                IF (F.focus # ef) & (keysum = {leftKey}) THEN
                    REPEAT TrackMouse(x, y, keys, keysum) UNTIL keys = {};
                    IF keysum = {leftKey} THEN RemoveSelection(F); RemoveCaret(F); PassSubFocus(F, ef); RETURN END
                ELSIF F.focus = ef THEN input.id := Oberon.track; input.keys := keysum; input.X := x; input.Y := y;
                    ef.handle(ef, input); RETURN
                END
            END;
            IF keysum # {} THEN TouchElem(F, x, y, keysum);
                IF keysum = {} THEN RETURN END
            END;
            IF leftKey IN keysum THEN
                Oberon.PassFocus(Viewers.This(F.X, F.Y)); pos0 := Pos(F, x, y);
                IF (F.carloc.pos = pos0) & (pos0 # F.text.len) THEN
                    IF F.hasSel & (F.selbeg.pos <= pos0) & (pos0 < F.selend.pos) THEN
                        LocateLine(F, y, loc); SetSelection(F, loc.org, loc.org + loc.line.span);
                        INCL(keysum, trackLine); TrackSelection(F, x, y, keysum)
                    ELSE
                        RemoveCaret(F);
                        SetSelection(F, WordBeg(F.text, pos0), WordEnd(F.text, pos0));
                        INCL(keysum, trackWord); TrackSelection(F, x, y, keysum)
                    END
                ELSE
                    RemoveSelection(F);
                    REPEAT
                        TrackMouse(x, y, keys, keysum); pos := Pos(F, x, y); SetCaret(F, pos)
                    UNTIL (keys = {}) OR (pos # pos0);
                    IF pos # pos0 THEN
                        RemoveCaret(F);
                        IF pos < pos0 THEN i := pos; pos := pos0; pos0 := i END;
                        SetSelection(F, pos0, pos); TrackSelection(F, x, y, keysum)
                    END
                END
            ELSIF middleKey IN keysum THEN TrackWord(F, x, y, pos, keysum);
                IF keysum # cancel THEN Call(F, pos, keysum = {middleKey, leftKey}) END
            ELSE DrawCursor(x, y)
            END
        END
    END Edit;
    (** General **)
    PROCEDURE Copy (SF, DF: Frame);
    BEGIN
        DF.handle := SF.handle; DF.text := SF.text; DF.org := SF.org;
        DF.col := SF.col; DF.left := SF.left; DF.right := SF.right; DF.top := SF.top; DF.bot := SF.bot;
        DF.barW := SF.barW; DF.hasCar := FALSE; DF.hasSel := FALSE; DF.showsParcs := SF.showsParcs;
        DF.focus := NIL; DF.trailer := NIL
    END Copy;
    PROCEDURE Handle* (f: Display.Frame; VAR msg: Display.FrameMsg);
        VAR F, F1: Frame; pos: LONGINT;
    BEGIN F := f(Frame);
        IF msg IS Oberon.InputMsg THEN
            WITH msg: Oberon.InputMsg DO
                IF msg.id = Oberon.consume THEN Write(F, msg.ch, msg.fnt, msg.col, msg.voff)
                ELSIF msg.id = Oberon.track THEN
                    IF (msg.X < F.X + F.barW) THEN        (*CM  18.11.94 *)
                        scrollBar.HandleScrollBar(F, msg.X, msg.Y, msg.keys)
                    ELSIF (msg.X >= F.X + F.barW) THEN
                        Edit(F, msg.X, msg.Y, msg.keys)
                    END
                END
            END
        ELSIF msg IS Oberon.ControlMsg THEN
            WITH msg: Oberon.ControlMsg DO
                IF msg.id = Oberon.defocus THEN RemoveCaret(F)
                ELSIF msg.id = Oberon.neutralize THEN
                    RemoveCaret(F); RemoveSelection(F); PassSubFocus(F, NIL); NotifySubFrames(F, msg)
                ELSE NotifySubFrames(F, msg)
                END
            END
        ELSIF msg IS Oberon.CopyMsg THEN
            WITH msg: Oberon.CopyMsg DO
                IF msg.F = NIL THEN NEW(F1); msg.F := F1 END;
                Copy(F, msg.F(Frame))
            END
        ELSIF msg IS UpdateMsg THEN NotifySubFrames(F, msg);
            WITH msg: UpdateMsg DO
                IF msg.text = F.text THEN Update(F, msg) END
            END
        ELSIF msg IS InsertElemMsg THEN
            IF F.hasCar THEN pos := F.carloc.pos;
                PickAttributes(W, Texts.ElemChar, F.text, pos, Oberon.CurFnt, Oberon.CurCol, Oberon.CurOff);
                Texts.WriteElem(W, msg(InsertElemMsg).e);
                Texts.Insert(F.text, pos, W.buf);
                SetCaret(F, pos + 1)
            END
        ELSIF msg IS Oberon.SelectionMsg THEN NotifySubFrames(F, msg);
            WITH msg: Oberon.SelectionMsg DO
                IF F.hasSel & (F.time > msg.time) THEN
                    msg.text := F.text; msg.beg := F.selbeg.pos; msg.end := F.selend.pos; msg.time := F.time
                END
            END
        ELSIF msg IS Oberon.CopyOverMsg THEN NotifySubFrames(F, msg);
            WITH msg: Oberon.CopyOverMsg DO
                IF F.hasSel THEN Write(F, DEL, NIL, 0, 0) END;
                IF F.hasCar THEN Texts.Save(msg.text, msg.beg, msg.end, B);
                    Texts.Insert(F.text, F.carloc.pos, B); SetCaret(F, F.carloc.pos + (msg.end - msg.beg))
                END
            END
        ELSIF msg IS MenuViewers.ModifyMsg THEN
            WITH msg: MenuViewers.ModifyMsg DO
                F.handle(F, neutralize); Resize(F, F.X, msg.Y, F.W, msg.H)
            END
        ELSIF msg IS SelectMsg THEN NotifySubFrames(F, msg);
            WITH msg: SelectMsg DO
                IF (msg.text = F.text) & ~F.hasSel THEN Oberon.RemoveMarks(F.X, F.Y, F.W, F.H);
                    F.handle(F, neutralize);
                    SetSelection(F, msg.beg, msg.end); F.time := msg.time;
                    IF F.hasSel THEN F.selbeg.pos := msg.beg; F.selend.pos := msg.end END
                END
            END
        ELSE NotifySubFrames(F, msg)
        END
    END Handle;
    PROCEDURE Open* (F: Frame; T: Texts.Text; pos: LONGINT);
    BEGIN
        F.handle := Handle; F.text := T; F.org := pos; F.col := Display.black;
        F.left := left; F.right := right; F.top := top; F.bot := bot;
        F.barW := barW; F.hasCar := FALSE; F.hasSel := FALSE; F.showsParcs := FALSE; F.trailer := NIL
    END Open;
    PROCEDURE NotifyDisplay* (T: Texts.Text; op: INTEGER; beg, end: LONGINT);
        VAR msg: UpdateMsg;
    BEGIN
        msg.text := T; msg.id := op; msg.beg := beg; msg.end := end; Viewers.Broadcast(msg)
    END NotifyDisplay;
    PROCEDURE Text* (name: ARRAY OF CHAR): Texts.Text;
        VAR text: Texts.Text;
    BEGIN
        NEW(text); Texts.Open(text, name); text.notify := NotifyDisplay; RETURN text
    END Text;
    PROCEDURE NewText* (T: Texts.Text; pos: LONGINT): Frame;
        VAR frame: Frame;
    BEGIN
        NEW(frame); Open(frame, T, pos);
        RETURN frame
    END NewText;
    PROCEDURE NewMenu* (name, commands: ARRAY OF CHAR): Frame;
        VAR T, T1: Texts.Text; buf: Texts.Buffer; frame: Frame; fn: ARRAY 32 OF CHAR; i: INTEGER;
    BEGIN
        T := Text("");
        Texts.WriteString(W0, name); Texts.WriteString(W0, " | "); Texts.Append(T, W0.buf);
        IF commands[0] = "^" THEN
            i := 0; REPEAT INC(i); fn[i-1] := commands[i] UNTIL commands[i] = 0X;
            IF Files.Old(fn) = NIL THEN
                Texts.WriteString(W0, "System.Close  System.Grow  System.Copy Edit.Store "); Texts.Append(T, W0.buf)
            ELSE
                NEW(T1); Texts.Open(T1, fn);
                NEW(buf); Texts.OpenBuf(buf); Texts.Save(T1, 0, T1.len, buf); Texts.Append(T, buf)
            END
        ELSE
            Texts.WriteString(W0, commands); Texts.Append(T, W0.buf)
        END;
        NEW(frame); Open(frame, T, 0);
        frame.col := Display.white; frame.left := 6; frame.top := 0; frame.bot := 0; frame.barW := 0;
        RETURN frame
    END NewMenu;
(* CM 19.07.94 *)
    PROCEDURE (obj: ScrollBarElem) LineDown;
    VAR F: Display.Frame; loc: Location;
    BEGIN
        F := obj.F;
        WITH F: Frame DO
            Show(F, F.org  - 1);
            LocateLine(F, F.Y+F.bot, loc);
            obj.Update(FALSE, F.text.len, F.org, loc.org + loc.line.len)
        ELSE
        END
    END LineDown;
    PROCEDURE (obj: ScrollBarElem) LineUp;
    VAR F: Display.Frame; loc: Location;
    BEGIN
        F := obj.F;
        WITH F: Frame DO
            Show(F, F.trailer.next.next.org);
            LocateLine(F, F.Y+F.bot, loc);
            obj.Update(FALSE, F.text.len, F.org, loc.org + loc.line.len)
        ELSE
        END
    END LineUp;
    PROCEDURE (obj: ScrollBarElem) PageDown;
    VAR F: Display.Frame; loc: Location;
    BEGIN
        F := obj.F;
        WITH F: Frame DO
            LocateLine(F, F.Y + F.bot, loc);
            Show(F, loc.org);
            LocateLine(F, F.Y + F.bot, loc);
            obj.Update(FALSE, F.text.len, F.org, loc.org + loc.line.len)
        ELSE
        END
    END PageDown;
    PROCEDURE (obj: ScrollBarElem) PageUp;
    VAR F: Display.Frame;loc: Location; delta: INTEGER; org: LONGINT;
    BEGIN
        F := obj.F;
        WITH F: Frame DO
            LocateLine(F, F.Y + F.H - 1, loc);
            org := loc.org;
            delta := loc.y - F.Y - F.bot;
            Back(F, delta, org);
            Show(F, org);
            LocateLine(F, F.Y + F.bot, loc);
            obj.Update(FALSE, F.text.len, F.org, loc.org + loc.line.len)
        ELSE
        END
    END PageUp;
    PROCEDURE (obj: ScrollBarElem) UpdateView(pressed: BOOLEAN; dY: INTEGER);
    VAR F: Display.Frame; org: LONGINT; t: TextLine;
    BEGIN
        F := obj.F;
        IF dY # obj.sliderdY THEN
            WITH F: Frame DO
                org := (F.text.len * dY) DIV (obj.h - obj.w*2 - obj.minW - obj.minW DIV 2);
                IF dY > obj.sliderdY THEN
                    IF (org <= F.org) OR (org < F.trailer.next.next.org) THEN org := F.trailer.next.next.org
                    END
                ELSIF dY < obj.sliderdY THEN
                    IF org >= F.org THEN org := F.org - 1  END
                END;
                IF org # F.org THEN
                    Show(F, org);
                    obj.Update(pressed, F.text.len, F.org, F.trailer.org+F.trailer.len)
                END
            ELSE
            END
        END
    END UpdateView;
    PROCEDURE (obj: ScrollBarElem) TrackSlider(VAR mx, my : INTEGER; VAR keysum : SET);
    VAR pos: LONGINT; F: Display.Frame;
    BEGIN
        obj.TrackSlider^(mx, my, keysum);
        F := obj.F;
        WITH F: Frame DO
            IF keysum = {middleKey, leftKey} THEN
                pos := F.text.len;
                Back(F, F.H - F.top - F.bot - 30 (* heuristic*), pos); Show(F,pos);
                obj.CalculateSliderDim(F.text.len, F.org, F.trailer.org);
                obj.DrawSlider(FALSE)
            ELSIF keysum = {middleKey, rightKey} THEN
                obj.UpdateView(FALSE, 0)
            END
        ELSE
        END
    END TrackSlider;
    PROCEDURE (obj: ScrollBarElem) HandleScrollBar (F: Display.Frame; mx, my : INTEGER;
                                                                                        keysum : SET);
    BEGIN
        WITH F: Frame DO
            obj.SetDim(F.X, F.Y, F.barW -1, F.H);
            obj.CalculateSliderDim(F.text.len, F.org, F.trailer.org + F.trailer.len);
            used := TRUE;
            obj.HandleScrollBar^(F, mx, my, keysum);
            used := FALSE
        ELSE
        END
    END HandleScrollBar;
BEGIN
    Texts.OpenWriter(W); Texts.OpenWriter(W0);
    Texts.SetFont(W0, Fonts.Default); Texts.SetColor(W0, Display.white); Texts.SetOffset(W0, 0);
    neutralize.id := Oberon.neutralize;
    NEW(par);
    NEW(B); Texts.OpenBuf(B);
    menuH := Fonts.Default.height + 2;
    barW := menuH; left := barW + 6; right := 8; top := 6; bot := 6;            (*CM 08.08.94*)
    InitDefParc;
    NEW(scrollBar); scrollBar.Init;     used := FALSE;                                    (*CM 08.08.94*)
END TextFrames.