Please see http://forum.zkoss.org/question/85363/strange-behavior-of-contents_changed-for-tree-view-updates/ for a detailed description
Calling invalidate() is a workaround but I have performance concerns about this.
Please see http://forum.zkoss.org/question/85363/strange-behavior-of-contents_changed-for-tree-view-updates/ for a detailed description
Calling invalidate() is a workaround but I have performance concerns about this.