Wish AsyncMessage Selfcontrol...

Private Sub CallingSub
    Dim msg1() As Object = Array("Do you know what you're doing?","Caution", "Yes", "Cancel", "No", Null)

    Wait For(onceMsg(msg1)) Complete (success As Boolean)
    Log("Done 1: " & msg1(0))

    Wait For(onceMsg(msg1)) Complete (success As Boolean)
    Log("Done 2: " & msg1(0))

    'OR if no answer expected and no need to wait ...
    
    Dim msg2() As Object = Array("Be careful!","Caution")

    onceMsgNoWait(msg2)
    Log("Done 3")

    onceMsgNoWait(msg2)
    Log("Done 4")
End Sub

Public Sub onceMsg(msg() As Object) As ResumableSub
    If Not(msg(0) Is Int) Then
        Dim sf As Object = xui.Msgbox2Async(msg(0), msg(1), msg(2), msg(3), msg(4), msg(5))
        Wait For (sf) Msgbox_Result (result As Int)
        msg(0) = result
        Return True
    Else
        Return False
    End If
End Sub

Public Sub onceMsgNoWait(msg() As Object)
    If Not(msg(0) Is Int) Then
        xui.MsgboxAsync(msg(0), msg(1))
        msg(0) = 0
    End If
End Sub