With Q2 release we made some changes to the RadDocking control in order to improve its performance. This affects some visual parts and that's why we needed to change the control template. So if you're using a custom ControlTemplate, you should regenerate the default one from the 2011.2. 712 release and then customize it.
If this is not the case, please send us more details about your scenario. Thanks in advance
the Telerik team
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