All combo boxes are a combination of a list box and an edit. But Delphi
provides for three types of combo box styles:
Simple: an edit control is placed on top of a list box. Users can
choose from the list or type text in the edit box. Use this style for short
lists.
Drop-down: similar to the simple type, except that the list box
isn't displayed until a drop-down button is clicked. To be used for long
lists, or if there is not much room on the form.
Drop-down list: as with the drop-down style, the list isn't
visible at first. Users can click the drop-down button and chose from the
list, but they can't enter text in the edit portion. Use this type when you
want users to select only from a fixed set of choices.
Transparent color of a glyph
When you place a glyph (bitmap-picture) on a button, the color of the
pixel in the picture's lower-left corner will be used as the transparent
color. All pixels of that color will be transparent. If you don't want any
transparent parts on your button bitmap, make sure to use a color in the
lower-left corner that is not used anywhere else in the bitmap.
Line number of the cursor in a TMemo
Use this Windows API function to determine which line the cursor is
in: LineNumber :=
SendMessage(Memo1.Handle,EM_LINEFROMCHAR,memo1.Selstart,0);
Making a group of components visible / invisible
If you want to make part of a form to be visible only from time to time,
put these components on a separate Panel. Then, the Visible property of the
panel to true or false.
More lines in a hint
If you want to display more than a one line in the hint of a control, for
example of Button1, set it's property ShowHint to true. In the Object
Inspector, don't put anything in Button1's hint property. In the
FormCreate event handler of the form that contains Button1, add this line:
