Attach to Process...

...under the tools menu in Visual Studio seems to be a pretty handy thing to troubleshooting WinForms apps. If you have a WinForm app built out and installed somewhere and you want to use it while also setting breakpoints inside of libraries it uses, you may:

1. open the uncompiled code in Visual Studio
2. set break points
3. open the application
4. perform the Attach to Process...
5. browse the application as if one were browsing a web application via Cassini!

If the application has a .dll which is out of version with the code you have breakpoints in then you can't expect Visual Studio to wire up an association that will let you debug. (It is doing this based solely on what you have open and the .exe you attach to. It is making some logically assumptions.) So, you will want to update .dlls at your WinForms app before undertaking this process.