Addresses meter accessibility mentioned in bug #33

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

src/widgets/Meter.h

@@ -85,6 +85,8 @@ class MeterUpdateQueue
    MeterUpdateMsg  *mBuffer;
 };
 
+class MeterAx;
+
 class Meter : public wxPanel
 {
    DECLARE_DYNAMIC_CLASS(Meter)
@@ -185,6 +187,8 @@ class Meter : public wxPanel
    void OnMouse(wxMouseEvent &evt);
    void OnKeyDown(wxKeyEvent &evt);
    void OnContext(wxContextMenuEvent &evt);
+   void OnSetFocus(wxFocusEvent &evt);
+   void OnKillFocus(wxFocusEvent &evt);
 
    void OnAudioIOStatus(wxCommandEvent &evt);
 
@@ -263,7 +267,89 @@ class Meter : public wxPanel
    wxString  mLeftText;
    wxString  mRightText;
 
+   bool mIsFocused;
+   wxRect mFocusRect;
+
+   friend class MeterAx;
+
    DECLARE_EVENT_TABLE()
 };
 
+#if wxUSE_ACCESSIBILITY
+
+class MeterAx: public wxWindowAccessible
+{
+public:
+   MeterAx(wxWindow * window);
+
+   virtual ~ MeterAx();
+
+   // Performs the default action. childId is 0 (the action for this object)
+   // or > 0 (the action for a child).
+   // Return wxACC_NOT_SUPPORTED if there is no default action for this
+   // window (e.g. an edit control).
+   virtual wxAccStatus DoDefaultAction(int childId);
+
+   // Retrieves the address of an IDispatch interface for the specified child.
+   // All objects must support this property.
+   virtual wxAccStatus GetChild(int childId, wxAccessible** child);
+
+   // Gets the number of children.
+   virtual wxAccStatus GetChildCount(int* childCount);
+
+   // Gets the default action for this object (0) or > 0 (the action for a child).
+   // Return wxACC_OK even if there is no action. actionName is the action, or the empty
+   // string if there is no action.
+   // The retrieved string describes the action that is performed on an object,
+   // not what the object does as a result. For example, a toolbar button that prints
+   // a document has a default action of "Press" rather than "Prints the current document."
+   virtual wxAccStatus GetDefaultAction(int childId, wxString *actionName);
+
+   // Returns the description for this object or a child.
+   virtual wxAccStatus GetDescription(int childId, wxString *description);
+
+   // Gets the window with the keyboard focus.
+   // If childId is 0 and child is NULL, no object in
+   // this subhierarchy has the focus.
+   // If this object has the focus, child should be 'this'.
+   virtual wxAccStatus GetFocus(int *childId, wxAccessible **child);
+
+   // Returns help text for this object or a child, similar to tooltip text.
+   virtual wxAccStatus GetHelpText(int childId, wxString *helpText);
+
+   // Returns the keyboard shortcut for this object or child.
+   // Return e.g. ALT+K
+   virtual wxAccStatus GetKeyboardShortcut(int childId, wxString *shortcut);
+
+   // Returns the rectangle for this object (id = 0) or a child element (id > 0).
+   // rect is in screen coordinates.
+   virtual wxAccStatus GetLocation(wxRect& rect, int elementId);
+
+   // Gets the name of the specified object.
+   virtual wxAccStatus GetName(int childId, wxString *name);
+
+   // Returns a role constant.
+   virtual wxAccStatus GetRole(int childId, wxAccRole *role);
+
+   // Gets a variant representing the selected children
+   // of this object.
+   // Acceptable values:
+   // - a null variant (IsNull() returns TRUE)
+   // - a list variant (GetType() == wxT("list"))
+   // - an integer representing the selected child element,
+   //   or 0 if this object is selected (GetType() == wxT("long"))
+   // - a "void*" pointer to a wxAccessible child object
+   virtual wxAccStatus GetSelections(wxVariant *selections);
+
+   // Returns a state constant.
+   virtual wxAccStatus GetState(int childId, long* state);
+
+   // Returns a localized string representing the value for the object
+   // or child.
+   virtual wxAccStatus GetValue(int childId, wxString* strValue);
+
+};
+
+#endif // wxUSE_ACCESSIBILITY
+
 #endif // __AUDACITY_METER__