Addresses meter accessibility mentioned in bug #33

And also corrects the missing focus rectangle display on
the toolbar buttons on Linux.

src/widgets/AButton.h

@@ -159,6 +159,7 @@ class AButton: public wxWindow {
    std::vector<ImageArr> mImages;
 
    wxRect mFocusRect;
+   bool mForceFocusRect;
 
    std::auto_ptr<Listener> mListener;