Programmatically dismiss a MsgBox

Question

I have a master macro in an Excel file, \'file A\' that opens another Excel file, \'file B\'. On open, an add-in imports data into \'file B\'. I would like to close \'file B\' o

Answer 1

Since the "add-in" and Excel/VBA run in the same context, we cannot launch it and monitor its message-box within the same VBA application, because each VBA application is a single-threaded process. Fortunately however, there is a solution that can exploit the fact that different VBA applications run in different contexts, so they can run in parallel.

My suggested solution is to create a MS-Word document that is dedicated to monitoring and closing that message box. We need this in Word (or any other office application) in order to make the monitoring code and the addin's code run in parallel, in different contexts.

1- create a Word macro-enable document, named mboxKiller.docm and place it in some folder; i.e. C:\SO in my example. place this code in ThisDocument and save:

Private Declare PtrSafe Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare PtrSafe Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Public Sub WaitAndKillWindow()
    On Error Resume Next
    Dim h As Long: h = FindWindow(vbNullString, "Microsoft Excel")
    If h <> 0 Then SendMessage h, 16, 0, 0 ' <-- WM_Close
    Application.OnTime Now + TimeSerial(0, 0, 1), "WaitAndKillWindow"
End Sub

Private Sub Document_Open()
    WaitAndKillWindow
End Sub

2- In the Excel workbook's VBA, create a class module, named mboxKiller with this code:

Private killerDoc As Object

Private Sub Class_Initialize()
    On Error Resume Next
    Set killerDoc = CreateObject("Word.Application").Documents.Open(Filename:="C:\SO\mboxKiller.docm", ReadOnly:=True)
    If Err.Number <> 0 Then
        If Not killerDoc Is Nothing Then killerDoc.Close False
        Set killerDoc = Nothing
        MsgBox "could not lauch The mboxKiller killer. The message-box shall be closed manuallt by the user."
    End If
End Sub

Private Sub Class_Terminate()
    On Error Resume Next
    If Not killerDoc Is Nothing Then killerDoc.Application.Quit False
End Sub

3- Testing and Usage. In a normal class Module, place the following code and test the procedure

Sub Test() ' <-- run this for testing after finishing the setup
    Dim killer: Set killer = New mboxKiller
    simulateAddin
    simulateAddin
    simulateAddin
End Sub

' Procedure supposed to do some calculation then display a message box
Private Sub simulateAddin()
    Dim i As Long
    For i = 0 To 1000: DoEvents: Next ' simulates some calculations
    MsgBox "This is a message box to simulate the message box of the addin." & VbCrLf & _
    "It will be automatically closed by the Word app mboxKiller"
End Sub