Subclassing questions

[Unleash]

So, as a follow up on my previous thread:

http://www.mrexcel.com/forum/showthread.php?p=2690602#post2690602

Which miserably failed. I have been testing and writing code all day to find out why things are not working.

I now know that the problem lies within the "hooking" of the userform. But I don't know why it keeps terminating when coming there. these are the two parts that do the hooking:

Private Sub List_Hook()
    'Maakt de Hook alleen als deze nog niet bestaat
    If Not blnHooked Then
        WheelHook FlensDefinitie
        blnHooked = True
    End If
End Sub

Public Sub WheelHook(ClientForm As UserForm)
    hWnd_UserForm = FindWindow("ThunderDFrame", ClientForm.Caption)
    lngWndProc = SetWindowLong(hWnd_UserForm, GWL_WNDPROC, AddressOf WindowProc)
End Sub

The first one is called by mouseover events from the listboxes and from the Userform itself. Although when the mouseover event for the Userform gets raised, it isnt the hookup but the unhook path that is run. These are the subs for the unhooking:

Private Sub UserForm_MouseMove(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single)
    LH = 0
    'Vernietigd de hook als de muis niet op de control is.
    Call List_UnHook
End Sub

 Private Sub List_UnHook()
    'Vernietigd de hook alleen als deze al bestaat
    If blnHooked Then
        WheelUnHook
        blnHooked = False
    End If
End Sub

Public Sub WheelUnHook()
Dim lRet As Long
    lRet = SetWindowLong(hWnd_UserForm, GWL_WNDPROC, lngWndProc)
End Sub

The code fails the moment that the cursor comes onto the Userform, and the Mousemove event is raised. But since "blnHooked" is "false" from the beginning, nothing should happen.

Any idea on why the MouseMove event causes a crash??

Any help will be greatly appreciated!

 

[RoryA]

Yeah, but that's for Access forms which are a totally different beast!
Personally, I'd probably avoid popups in that function - just suppress the errors.

 

[Unleash]

Hmm I was afraid of that...

So back to hooking then. Ill keep you posted on my progress.