I am evaluating the docking controls at the moment and have a few issues.
Is there an easy way to tell when a DocumentPane becomes active. There looked to be a promising event on the DockingManager (DockTabChanged) but this doesn't seem to get fired when tabs are added or deleted or the document pane is split.
The DockingWindow activate event seems to allow me to do what I want, but I have to add event handlers to each Document (which is doable but a pain). However the event fires twice for each activation (which is a pain to deal with). This is evident in your TabbedDocument sample (2009 Q1).