A:  This will work for a TPanel.

procedure TForm1.Panel1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
const
  SC_DragMove = $F012;
begin
  ReleaseCapture;
  (sender as TWinControl).perform(WM_SysCommand, SC_DragMove, 0);
end;