Private Sub Command1_Click()
Call Form_MouseDown(vbLeftButton, vbShiftMask, 0, 0)
End Sub
Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Shift Then
MsgBox ("Shift down")
Else
MsgBox ("Shift NOT down")
End If
End Sub
Use that to test it out for yourself. If you were testing with a CONTROL_Click event, the MouseDown event may have registered first...