After the first call to BView::InvalidateLayout() further invocations don't

invoke the layout's InvalidateLayout() anymore. This could cause problems when
the layout caches layout related information and also updates those on calls
other than LayoutView(). A call to such a method after an InvalidateLayout()
would mark the cached info valid and the layout would use the cached info
until the first InvalidateLayout() after the next LayoutView(), even if
BView::InvalidateLayout() had been called again in the meantime.

* Introduced a new method BView::ResetLayoutInvalidation(), which must be
  called by layout implementations whenever they have updated their cached
  information and need further InvalidateLayout() notifications.
* Adjusted the existing layout implementations to use the method.

Fixes bug #4047.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@31316 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/interface/View.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2006, Haiku.
+ * Copyright 2001-2009, Haiku.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -532,6 +532,7 @@ public:
 			void			EnableLayoutInvalidation();
 			void			DisableLayoutInvalidation();
 			bool			IsLayoutValid() const;
+			void			ResetLayoutInvalidation();
 
 			BLayoutContext*	LayoutContext() const;