Force app menu to auto-layout before recomputing scroll limits.

This makes Deskbar correctly calulate the scroll limits in the case
when scrollbars are attached but not due to an app being added or
removed for example because the icon sizes increased.

src/apps/deskbar/BarView.cpp

@@ -515,6 +515,8 @@ TBarView::PlaceApplicationBar()
 
 	SizeWindow(screenFrame);
 	PositionWindow(screenFrame);
+	fExpando->DoLayout();
+		// force menu to autosize
 	CheckForScrolling();
 
 	Window()->UpdateIfNeeded();