Sometimes when using the treeview in TriStateMode I wish I could have the ability to uncheck all the children of an indeterminate parent with one click. Currently when a parent is in indeterminate mode and you click on it, it will activate it and all it's 
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Reason for Decline:
This is a custom requriement and could be implemented as application logic based on this example:
http://www.telerik.com/help/wpf/radtreeview-howto-tri-state-mvvm.html