Perform wxAuiToolBar idle updates from UpdateWindowUI(), not OnIdle().

No real changes, just optimize the idle updates by doing it from (less often
called) UpdateWindowUI() instead of EVT_IDLE handler.

Closes #10075.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69594 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/aui/auibar.h

@@ -577,6 +577,9 @@ public:
     wxSize GetHintSize(int dockDirection) const;
     bool IsPaneValid(const wxAuiPaneInfo& pane) const;
 
+    // Override to call DoIdleUpdate().
+    virtual void UpdateWindowUI(long flags = wxUPDATE_UI_NONE);
+
 protected:
 
     virtual void OnCustomRender(wxDC& WXUNUSED(dc),