I just wanted to follow up on this issue.
The UIAutomation peer has been fixed so that it correctly displays the contents of the tab.
Since there is just one content loaded in the VisualTree at a time, we cannot show the content of TabItems that are not selected. I do not expect that we will be change this.
The fixes should be available in the next internal build.
I have attached a simple project that includes the changes, you can see how it works with UISpy if you wish.
Your Telerik Points have been updated.
Any other feedback on the UIAutoamtion is welcome,
the Telerik team