The following example shows how to move a window control at runtime by holding down the control key and clicking the left mouse button. This method will not work with non-window controls such as TLabel components. Example:

procedure TForm .Button MouseDown(Sender: TObject; Button:
  TMouseButton; Shift: TShiftState; X, Y: Integer);
{$IFNDEF WIN32}
var
  pt : TPoint;
{$ENDIF}
begin
  if ssCtrl in Shift then begin
    ReleaseCapture;
    SendMessage(Button .Handle, WM_SYSCOMMAND, 6 458, 0);
   {$IFNDEF WIN32}
    GetCursorPos(pt);
    SendMessage(Button .Handle,
                WM_LBUTTONUP,
                MK_CONTROL,
                Longint(pt));
   {$ENDIF}
  end;
end;