In the TreeView there is a known issue with the drag/drop feature in zoomed browser and we will do our best to fix it for the Q3 release.
As for the TreeView with ContextMenu issue - it is caused by a bug in Silverlight, which we have reported. We hope that it will be fixed for the RTM release of SL5, but I cannot give you a specific promise.
All the best,
the Telerik team
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