Cannot access x:key element

Hi,

  I've posted similar question in DesktopTesting group but didn't get any response, so I'll try here.

  As part of the test I'm writing I need to check an icon that's been drawn from a file. So I wanted to check the filename to verify that the correct icon is put on screen. When I Snoop the element I see that the filename is defined as an "x:key" (see attached)

The hierarchy is the following :

 IconRectangle (System.Windows.Shapes.Rectangle)

  |__Fill(System.Windows.Media.DrawingBrush)

          |__x:Key (System.String) = "DialogHistoryOutgoingActiveIcon"

Unfortunately I'm unable to access the x:Key from TestComplete (v10.6).  I've added Rectangle and DrawingBrush classes to the Composite Controls, but x:Key is still not accessible

Is there a way to get to this element ?

Thank you in advance!

    Yuri