Add a possibility to beep on no match to wxGenericTreeCtrl.

For consistency with Windows, allow to optionally generate a beep when
incremental search in the tree control doesn't find anything.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72638 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/treectrl.h

@@ -349,6 +349,10 @@ public:
     virtual void EndEditLabel(const wxTreeItemId& item,
                               bool discardChanges = false) = 0;
 
+        // Enable or disable beep when incremental match doesn't find any item.
+        // Only implemented in the generic version currently.
+    virtual void EnableBellOnNoMatch(bool WXUNUSED(on) = true) { }
+
     // sorting
     // -------