If you need to debug your own add-in for Tabs Studio or an existing one (all Tabs Studio add-ins come with source code) you can do it with the following steps (from the add-ins documentation):
- Remove your add-in from the TabsStudioAddins directory and start VS.
- In your add-in project set the Build – Output path to your TabsStudioAddins directory
(e.g. C:\Users\myadmin\Documents\Visual Studio 2008\Addins\TabsStudioAddins).
- In your add-in project set Debug – Start external program to VS
(e.g. C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\devenv.exe).
- Start Debugging as usual.
Well, you can do it with VS 2008 and VS 2010 RTM, but not with VS 2010 SP1. I read about this in the VS 2010 SP1 breaks add-in debugging targeting .NET Framework 2.0 blog post by Carlos Quintero. Tabs Studio add-in targets .NET 3.5 and thus also affected by this problem.
The first workaround is to retarget your add-in to .NET 4.0 (of course, this add-in will no longer work in VS 2008 after that). You will also need to add System.Xaml to assembly references:
The second workaround is to create a dummy project targeting .NET Framework 4 and use it as the startup target for debugging (looks like VS 2010 SP1 is only interested in the target framework of the startup project, not the executable under debug):
You can also up vote this issue on the Microsoft Connect site.