reset parent frame tool/status bar pointer automatically when the bar is destroyed; this ensures that we're never left with dangling pointers and fixes a crash under Mac when MDI child frame with a toolbar is closed

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29923 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/statbar.cpp

@@ -61,6 +61,14 @@ wxStatusBarBase::~wxStatusBarBase()
     FreeWidths();
     FreeStacks();
     InitStyles();
+
+    // notify the frame that it doesn't have a status bar any longer to avoid
+    // dangling pointers
+    wxFrameBase *frame = wxDynamicCast(GetParent(), wxFrameBase);
+    if ( frame && frame->GetStatusBar() == this )
+    {
+        frame->SetStatusBar(NULL);
+    }
 }
 
 // ----------------------------------------------------------------------------