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/mgl/app.h

@@ -44,7 +44,6 @@ public:
 
     virtual void Exit();
     virtual void WakeUpIdle();
-    virtual bool Yield(bool onlyIfNeeded = FALSE);
 
     virtual wxVideoMode GetDisplayMode() const { return m_displayMode; }
     virtual bool SetDisplayMode(const wxVideoMode& mode);
@@ -52,6 +51,8 @@ public:
 private:
     DECLARE_DYNAMIC_CLASS(wxApp)
 
+    virtual bool DoYield(bool onlyIfNeeded, long eventsToProcess);
+
     wxVideoMode m_displayMode;
 };