Hi Gerry, Thanks for the answer. I'm read the "AvalonDock and MVVM" project of Ahsley Davis. He uses ManagedContent class of Avalon (especially in dico Dictionary contentMap, ..), but in the new AvalonDock version (of Dirkster99 Avalon free support release), i notice that this class MangedContent does not exist. If there is no bypass, I will do it another way (based on the Avalon example MVVMTestApp that comes with the AvalonDock source code). Regards.