толщиной в 1 пиксел.
Пример:
type
tform1 = class(tform)
private
{private declarations}
procedure wmncpaint(var msg : twmncpaint); message wm_ncpaint;
public
{public declarations}
end;
var
form1: tform1;
implementation
{$r *.dfm}
procedure tform1.wmncpaint(var msg: twmncpaint);
var
dc : hdc;
pen : hpen;
oldpen : hpen;
oldbrush : hbrush;
begin
inherited;
dc := getwindowdc(handle);
msg.result := 1;
pen := createpen(ps_solid, 1, rgb(255, 0, 0));
oldpen := selectobject(dc, pen);
oldbrush := selectobject(dc, getstockobject(null_brush));
rectangle(dc, 0,0, form1.width, form1.height);
selectobject(dc, oldbrush);
selectobject(dc, oldpen);
deleteobject(pen);
releasedc(handle, canvas.handle);
end;