{
MoveTo, LineTo example
The following code draws a line from the upper left corner of a form to the mouse position when the mouse is moved, creating a "rubber band" effect.
} 
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  { first call FillRect to paint the surface of the form.
  this removes any previously drawn lines (and anything else!) }
  Canvas.FillRect(ClientRect);
  Canvas.MoveTo(0, 0);
  Canvas.LineTo(X, Y);
end; 
