title: Prevent docking AvalonDock
body: <p>Is it possible to prevent docking one anchorable element to another one by using some filtering? For example, at viewmodel I can include some property <code>doctype</code>. For one anchorable element the value for <code>doctype</code> will be "a" and for the another one "b". How can I use property <code>doctype</code> to prevent docking if anchorable element with value "a" can't docking to anchorable element with <code>doctype</code> "b"? Maybe, there are other solutions for this.</p>