Active is not a boolean state that you can just bind to. The active pane is based on which pane has the keyboard focus. If you want to activate a pane then you need to put keyboard focus into the pane - that is essentially what the Activate method of the ContentPane does. Maybe you could create your own attached  behavior, set it on the ContentPane and set it to a binding to your object's property and when it changes to true then you can call the activate method on the pane.