The options window contains properties for the drawing tools, namely the Brush, the Pencil and the Eraser. The Opacity property is also used for the Gradient and the Text tools.
The group of four buttons in the extreme left part of the options window lets you set shape and mode for the drawing tools.
Shape may be either square or circle while mode may be freeform (you can draw whatever you like by holding the left mouse button down) or line (drawing in straight lines only).
The Size pull-down menu lets you customize the size of a drawing tool. The size ranges from 1 to 51 pixels.
The Type pull-down menu is disabled in this version.
The Opacity pull-down menu lets you specify how transparent the lines should be. 100% stands for a completely solid line while 0% stands for absolutely opaque.