generate EVT_SCROLL events for the standalong scrollbars, not EVT_SCROLLWIN

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@15579 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/univ/scrolbar.h

@@ -126,7 +126,7 @@ protected:
 
     // event handlers
     void OnIdle(wxIdleEvent& event);
-    
+
     // forces update of thumb's visual appearence (does nothing if m_dirty=FALSE)
     void UpdateThumb();
 
@@ -136,6 +136,9 @@ protected:
     // common part of all ctors
     void Init();
 
+    // is this scrollbar attached to a window or a standalone control?
+    bool IsStandalone() const;
+
 private:
     // total range of the scrollbar in logical units
     int m_range;