Totally stumped, please help!

[Acoustic]

I'm stumped! Here's what happens...I click my "go" menu to create a new instance of a form (in this case an MDIChild) and populate it with the controls in a frame that is on another form in the dll I'm referencing. (toward the end of the menu's sub I add the references that obj and objWind hold to a collection for use later on....)

Public Declare Function SetParent Lib "user32" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long

Private Sub mnugo_Click()
    Dim obj As Object
    Dim objWind As Object
    Dim tForm As frmChild
    
    Set obj = CreateObject("myProject.myClass")
    Set objWind = obj.getwindow
    Set tForm = New frmChild
    
    Call SetParent(objWind.hwnd, tForm.hwnd)
    
    mColObj.Add obj
    mColObjWind.Add objWind
    
    Set pluginwindow = Nothing
    Set plugin = Nothing
    Set tForm = Nothing
End Sub

This part works just fine...it does EXACTLY what I want it to...
But when I close the form (after having called the DestroyWindow API to remove the references to the controls in the dll) and then try to click the "go" menu again, it doesn't work. No errors occurr, but when the "SetParent" API is called, (which normally returns the hWnd of the dll form's frame via objWind.hwnd), no hWnd value is returned. The value is just 0, and the MDIChild form isn't populated with anything...

I can't figure out for the life of me why this is. If you have any ideas at all please let me know. I can post more code...and more detailed code... if you need, just say so

Thanks!

[Acoustic]

*Sigh*

[jim mcnamara]

Use can the
Set whatever = Nothing syntax.

But it doesn't work in the client the way you think. It actually calls the destructor for the class to do the dirty work.

1. In the destructor for your class you need to call
SendMessage(hWnd,WM_QUIT) then WM_DESTROY for all the windows you created (controls are mostly windows, except VB labels which you can ignore).

2. Call EnumChildWindows for the parent form to get all the hWnds so you can WM_DESTROY them one by one

The reason this all bombs is that you have WndProcs for windows that no longer exists - still in memory. You have to get the window(control) to kill itself. VB controls do that when you do a set .###. = Nothing. You apparently are not doing that. Since 98% of your code isn't here, this is what I'm assuming is going on.

Note this from MSDN You don't have to mess with WM_NCDESTROY:

WM_NCDESTROY
The WM_NCDESTROY message informs a window that its nonclient area is being destroyed. The DestroyWindow function sends the WM_NCDESTROY message to the window following the WM_DESTROY message. WM_DESTROY is used to free the allocated memory object associated with the window. <<-- note!

The WM_NCDESTROY message is sent after the child windows have been destroyed. In contrast, WM_DESTROY is sent before the child windows are destroyed.

A window receives this message through its WindowProc function.

LRESULT CALLBACK WindowProc(
HWND hwnd, // handle to window
UINT uMsg, // WM_NCDESTROY
WPARAM wParam, // not used
LPARAM lParam // not used
);
Parameters

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