title: debug wpf by using sos.dll issue
body: <p>I am using sos.dll to find memory leak in wpf .
  And I found a wpf object was not released,
  then I tried to find out why it is not released by using <strong>!gcroot</strong> </p>
  
  <p>it gave me a warming that:</p>
  
  <p><strong>Please note that 6c369950 is not a valid object.</strong></p>
  
  <p>snippet of the debugging info </p>
  
  <pre><code>!dumpheap -type WPFUILib.MenuWindow
  Statistics:
        MT    Count    TotalSize Class Name
  0c12ef4c       14          224 WPFUILib.MenuWindow+&lt;&gt;c__DisplayClass2b
  03fdf624        2          816 WPFUILib.MenuWindow
  Total 16 objects
  
  !gcroot 03fdf624
  Note: Roots found on stacks may be false positives. Run "!help gcroot" for
  more info.
  Please note that 03fdf624 is not a valid object.
  </code></pre>