Move wxList::Member() to pseudo-template base list class.

Member() should be available in all list classes, not just specially crafted
list of wxObjects (wxList).

See #3616.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65789 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/carbon/nonownedwnd.cpp

@@ -722,8 +722,8 @@ wxMacTopLevelMouseEventHandler(EventHandlerCallRef WXUNUSED(handler),
 
         if ( currentMouseWindow->HandleWindowEvent(wxevent) )
         {
-            if ((currentMouseWindowParent != NULL) &&
-                (currentMouseWindowParent->GetChildren().Find(currentMouseWindow) == NULL))
+            if ( currentMouseWindowParent &&
+                 !currentMouseWindowParent->GetChildren().Member(currentMouseWindow) )
                 currentMouseWindow = NULL;
 
             result = noErr;