Can VB.net take control of a VBA form? - vb.net

Question

I have an Excel VBA macro containing a form. I would like for VB.net to either hide the form or take control of it and click the "X" button or the custom "Exit" button.
Does anybody have experience with this?

Answer 1

Sendkeys are highly unreliable.
If you can automate the Excel from VB.Net the I would recommend that. If you are interested in automating Excel from VB.Net then see this.
If you don't want to automate but want to directly handle it then I would recommend using the FindWindow and Sendmessage API to get control of the form. See this Example.
Let's say that there is a userform in Excel which looks like this
Use this code form VB.Net
CODE:
Imports System.Runtime.InteropServices
Imports System.Text
Public Class Form1
<DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function FindWindow( _
ByVal lpClassName As String, _
ByVal lpWindowName As String) As IntPtr
End Function
<DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function SendMessage(ByVal hWnd As IntPtr, _
ByVal Msg As UInteger, _
ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Boolean
End Function
Private Const WM_CLOSE = &H10
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim Ret As Integer
'~~> Get the handle of the Excel Userform named "Example"
Ret = FindWindow(vbNullString, "Example")
'~~> If Found
If Ret <> 0 Then
'~~> Close the Window
SendMessage(Ret, WM_CLOSE, CLng(0), CLng(0))
End If
End Sub
End Class