怎样在Tabcontrol上利用Tconvers画图(100分)

若直接画,会画在Form上,被Tabcontrol遮盖住,请教

procedure TForm1.Button1Click(Sender: TObject);
var
DC: HDC;
Canvas: TCanvas;
begin
DC:=GetDC(TabControl1.Handle);
try
Canvas:=TCanvas.Create;
try
Canvas.Handle:=DC;
Canvas.Rectangle(10, 10, 100, 100);
//爱怎么画就怎么画吧
finally
Canvas.Free
end
finally
ReleaseDC(TabControl1.Handle, DC)
end
end;

接受答案了.