mark all dtors which are virtual because base class dtor is virtual explicitly virtual themselves

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41020 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

demos/poem/wxpoem.h

@@ -29,7 +29,7 @@ class MyCanvas: public wxWindow
 {
 public:
     MyCanvas(wxFrame *frame);
-    ~MyCanvas();
+    virtual ~MyCanvas();
 
     void OnPaint(wxPaintEvent& event);
     void OnMouseEvent(wxMouseEvent& event);
@@ -47,7 +47,7 @@ class MainWindow: public wxFrame
 public:
     MyCanvas *canvas;
     MainWindow(wxFrame *frame, wxWindowID id, const wxString& title, const wxPoint& pos, const wxSize& size, long style);
-    ~MainWindow();
+    virtual ~MainWindow();
 
     void OnCloseWindow(wxCloseEvent& event);
     void OnChar(wxKeyEvent& event);