Initial/Best size fixes for wxRadioBox, wxSlider and wxStaticText on wxMSW

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@27083 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/radiobox.h

@@ -128,6 +128,9 @@ public:
         { SetBackgroundColour(bg); }
 
 protected:
+    // we can't compute our best size before the items are added to the control
+    virtual void SetInitialBestSize(const wxSize& WXUNUSED(size)) { }
+
     // subclass one radio button
     void SubclassRadioButton(WXHWND hWndBtn);