title: Is there a way to add your own controls to Blend's "Group Into" and "Change Layout Type" options?
body: <p>In Expression Blend 4, we can right click on an object in the Objects and Timeline panel to access the handy functions "Group Into" and "Change Layout Type":</p>
  
  <p><img src="https://i.stack.imgur.com/tKgZO.png" alt="enter image description here"></p>
  
  <p>However, what I really want often times is to be able to "group into" or "change layout type to" some of <strong>my own WPF content controls</strong>, such as a SunkenBorder, ClippingBorder, TransitionContentControl, etc.  Is there a way that we can tell Blend to also include some of our controls (or any non-standard WPF controls) in these lists?</p>
  
  <p><strong>Update:</strong></p>
  
  <p>After I originally asked this question I had the idea to take a look at the source code of some of the panels that Expression Blend does include in its lists (Grid, StackPanel, etc), in the attempt to find a class metadata attribute that Blend might be paying attention to in order to populate these lists.  I was hoping to find some attribute analogous to the <a href="http://blogs.msdn.com/b/jnak/archive/2008/01/17/showing-attached-properties-in-the-cider-wpf-designer.aspx" rel="nofollow noreferrer">ones you can specify for your own attached properties</a> that allow them to show up in Blend or Visual Studio in their property panels.  Unfortunately I did not find any such class attribute, so it appears that Sorskoot is correct, that we cannot add to these lists that Blend shows.</p>