void __fastcall TForm1::BackgroundMouseMove(TObject *Sender,
      TShiftState Shift, int X, int Y)
{
        if ( Shift.Contains(ssLeft) ) // this tests if we are pressing the left button of the mouse
       {   
               Form1->Left = Mouse->CursorPos.x;
               Form1->Top = Mouse->CursorPos.y;
        }
}