check in the 'selective yield' patch (see ticket #10320):

- implements YieldFor() with event filtering for wxMSW and wxGTK,
  adds TODO markers in other ports;
- replaces wxYield() in GTK's clipboard code with a wxTheApp->YieldFor() call, thus fixing possible reentrancies 
(and modifies clipboard sample to test synchronous IsSupported calls)
- replaces wxYieldIfNeeded() calls in wxProgressDialog with wxTheApp->YieldFor() calls, so that it processes only 
UI/user-input events, thus fixing the race condition visible in the "thread" sample
- documents the new functions


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58654 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/timer.h

@@ -172,6 +172,7 @@ public:
 
     // implement the base class pure virtual
     virtual wxEvent *Clone() const { return new wxTimerEvent(*this); }
+    virtual wxEventCategory GetEventCategory() const { return wxEVT_CATEGORY_TIMER; }
 
 private:
     wxTimer* m_timer;