title: Create a visualtree off of a control template in code
body: <p>This is a follow up question to a previous question, wich didn't really get me anywhere:
   <a href="https://stackoverflow.com/questions/7281264/deterministic-and-asynchronous-field-validation-in-wpf">deterministic and asynchronous field validation in WPF</a></p>
  
  <p>Since WPF doesn't support <a href="http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifydataerrorinfo%28v=vs.95%29.aspx" rel="nofollow noreferrer">INotifyDataErrorInfo</a> it seems, that I need to implement something like that myself (please correct me if I am wrong here). I need this because I want the ViewModel to trigger when to display special ErrorTemplates for certain fields (e.g. after the click of a button or after the end of a long running async validation operation or when the internal state changes in a way that certain fields suddenly become invalid). </p>
  
  <p>I am considering to write a custom markup extension or behavior for this. It listens to my version of <code>INotifyDataErrorInfo</code> implemented by the ViewModel and creates a VisualTree from a special wellknown ErrorTemplate defined in XAML once the <code>ErrorsChanged</code> event was raised.</p>
  
  <p>Once I have defined that template in XAML, how do I find it from my behavior/expression, materialize an actual  visual tree out of it and then display it (probably somehow on an adorner layer) at the right field entry on my form?</p>