Allow reparenting wxPropertyGrid(Manager) to work; Show error and suggest calling wxPropertyGrid::OnTLPChanging() if top-level parent changed indirectly.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60989 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/propgrid/propgrid.h

@@ -697,6 +697,20 @@ public:
     */
     bool IsFrozen() const;
 
+    /**
+        Call this any time your code causes wxPropertyGrid's top-level parent
+        to change.
+
+        @param newTLP
+            New top-level parent that is about to be set. Old top-level parent
+            window should still exist as the current one.
+
+        @remarks This function is automatically called from wxPropertyGrid::
+                 Reparent() and wxPropertyGridManager::Reparent(). You only
+                 need to use it if you reparent wxPropertyGrid indirectly.
+    */
+    void OnTLPChanging( wxWindow* newTLP );
+
     /**
         Refreshes any active editor control.
     */