ImplAddDel() is being called at places like line 209 of event.cxx

And then there is
Application::ImplCallEventListeners( aEvent );	//from line 209 of event.cxx

    if ( aDelData.IsDead() )
        return;

    if (!mpWindowImpl->maEventListeners.empty())
    {
        // Copy the list, because this can be destroyed when calling a Link...
        std::vector<Link<VclWindowEvent&,void>> aCopy( mpWindowImpl->maEventListeners );
        for ( Link<VclWindowEvent&,void>& rLink : aCopy )
        {
            if (aDelData.IsDead()) break;
            // check this hasn't been removed in some re-enterancy scenario fdo#47368
            if( std::find(mpWindowImpl->maEventListeners.begin(), mpWindowImpl->maEventListeners.end(), rLink) != mpWindowImpl->maEventListeners.end() )
                rLink.Call( aEvent );
        }
    }

    if ( aDelData.IsDead() )
        return;

After this ImplRemoveDel() is called	//line 232 of event.cxx
-------------------------------------------------------------------------------------------------------------------------
So maybe, what you have in mind is something like:
1.	VclPtr<vcl::Window> temp_mpWindow = aDelData.mpWindow;	//Instead of line 209 from above example
2.	I will need help with what is required here
And then there is part from above example
.....
3.	//ImplRemoveDel comes here which is to be replaced with just 	//Instead of line 232 from above example
	if ( IsDisposed() ){
        return;
	}
4. And something more if required.

The reason I'm not able to fill in parts 2 and 4 is because I do not understand the connection between
IsDisposed() and aDelData.mpWindow

IsDisposed() does : " return !mpWindowImpl; " as a bool.
mpWindowImpl is a pointer of type WindowImpl ie WindowImpl* mpWindowImpl