made ShouldPreventAppExit() public

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38681 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/html/helpfrm.h

@@ -105,11 +105,11 @@ public:
     // Override to add custom buttons to the toolbar
     virtual void AddToolbarButtons(wxToolBar* WXUNUSED(toolBar), int WXUNUSED(style)) {};
 
-protected:
     // we don't want to prevent the app from closing just because a help window
     // remains opened
     virtual bool ShouldPreventAppExit() const { return false; }
 
+protected:
     void Init(wxHtmlHelpData* data = NULL);
 
     void OnCloseWindow(wxCloseEvent& event);