I apologize for any inconvenience this problem may have caused you.

I was able to reproduce the reported problem in my local end and will have this forwarded to ClientUI development team for further investigation. Should I hear any news regarding this, I will certainly let you know.

Any further word on a fix?

The ClientUI development team is currently investigating what may cause this problematic behavior. When ready, I can provide you with the nightly-build hotfix (the pre-release version) to be evaluated on your end.

I will keep you informed with any news I heard from the team regarding this.

Any idea is this problem has been fixed yet?

This problem has been filed under Bug 1434: Clicking on TabItem in Visual Studio Design Mode Doesn’t Open TabItem. Currently the hotfix for this reported problem is not available yet.

I can help by raising the priority for your reported problem.

This has now been magically fixed. I can click on the tabs in design mode and the tabs open and display properly. The only thing I have done lately is install Visual Studio 2012 Service Pack 3. I wonder if something in the service pack fixed it.

Bill

I have re-checked the reported problem filed under Bug 1434 using Visual Studio 2012 Update 3 and found that the problem does no longer exist. Thank you very much for the helpful information.

Once again, thank you for your message.