Added isosurf wxGLCanvas sample, cured OnPaint bug (missing wxPaintDC object)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@553 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

utils/glcanvas/samples/cube/cube.cpp

@@ -29,9 +29,6 @@
 
 #include "cube.h"
 
-// This statement initializes the whole application and calls OnInit
-MyApp myApp;
-
 IMPLEMENT_APP(MyApp)
 
 // `Main program' equivalent, creating windows and returning main app frame
@@ -125,6 +122,10 @@ TestGLCanvas::~TestGLCanvas(void)
 
 void TestGLCanvas::OnPaint( wxPaintEvent& event )
 {
+    // This is a dummy, to avoid an endless succession of paint messages.
+    // OnPaint handlers must always create a wxPaintDC.
+    wxPaintDC dc(this);
+
     if ( !GetContext() )
         return;