Declare Function GetAsyncKeyState Lib "USER32" (Byval vKey As Long) As Long

Sub Postopen(Source As Notesuidocument)
    Dim state
    For i = 0 To 5000
        state = GetAsyncKeyState(17)
    Next
    If state <> 0 Then
        Msgbox "Ctrlキーが押されています。"
    End If
End Sub