procedure TForm1.Panel1MouseDown(Sender: TObject; Button: TMouseButton; 
   Shift: TShiftState; X, Y: Integer); 
const 
  SC_DragMove = $F012;  { a magic number } 
begin 
  ReleaseCapture; 
  panel1.perform(WM_SysCommand, SC_DragMove, 0); 
end;