Title: How to make a polygon hole on a form
type
PtsType = array [0..15, 0..1] of Integer;
const
Pts: PtsType = ((0, 0), (800, 0), (800, 600),
(200, 600), (200, 220), (300, 280),
(265, 205), (350, 117), (205, 170),
(120, 90), (130, 200), (60, 350), (200, 220),
(200, 600), (0, 600), (0, 0));
procedure TForm1.Button1Click(Sender: TObject);
var
HRegion1: THandle;
begin
HRegion1 := CreatePolygonRgn(Pts, SizeOf(Pts) div 8, alternate);
SetWindowRgn(Handle, HRegion1, True);
end;