RemoveEventListener on self again

...as otherwise base class ~Window would call into WindowEventListener with
this no longer a SwSidebarWin.

Change-Id: Icfe942eef9a0adb58a59397b4f41514e0c696543

sw/source/uibase/docvw/SidebarWin.cxx

@@ -185,6 +185,8 @@ SwSidebarWin::~SwSidebarWin()
         mpVScrollbar = 0;
     }
 
+    RemoveEventListener( LINK( this, SwSidebarWin, WindowEventListener ) );
+
     AnchorOverlayObject::DestroyAnchorOverlayObject( mpAnchor );
     mpAnchor = NULL;