How to debug Visual Studio 2012 instance design-time

Question

I'm developing a WPF MarkupExtension and encountered errors during design time. With the previous version of Visual Studio 2010 it was possible to start a second instance of Visual Studio 2010 and attach to the process of the already-running instance, setting breakpoints and debugging the design time behavior.

In Visual Studio 2012 however I can attach to the process of another Visual Studio 2012 as well, but no symbols are loaded in the second instance and therefor I'm not able to debug the design time as with Visual Studio 2010.

How do I get this debugger running?

Things I've tried:

• "devenv.exe /RootSuffix Exp" trick without success
• Always execute as Administrator
• Load all or default symbols
• Debug with and without native code (attach process)
• Debug with and without .NET 4 code (attach process)

Answer 1

In Visual Studio 2012, the WPF designer runs in a separate process. Try fiddling with that process. It should be easy to find out the process name.