Private Declare Sub mouse_event Lib "user32" (ByVal dwFlags As Long, ByVal dx As Long, ByVal dy As Long, ByVal cbuttons As Long, ByVal dwExtraInfo As Long)
Private Const MOUSEEVENTF_LEFTUP = &H4
Private Const MOUSEEVENTF_RIGHTUP = &H10

Private Sub DataGrid1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
  Call mouse_event(MOUSEEVENTF_LEFTUP, 0&, 0&, 1, 0)
End Sub