Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

procedure TForm1.PanelTopMouseDown(Sender: TObject;
   Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
 const
   SC_DRAGMOVE = $F012;
 begin
   if (Button = mbLeft) then
   begin
     ReleaseCapture;
     (Self as TControl).Perform(WM_SYSCOMMAND, SC_DRAGMOVE, 0);
   end;
 end;