Hi,
I'm trying to think of a way that we can solve this problem for you without needing to introduce an additional filter to the tests window (which is already quite overloaded).
Do you perhaps have a particular convention for how you label test projects? For example, most projects usually use the following form:
MyProject.Code
MyProject.Code.Tests
If this is the case, you may be able to use the wildcard search options in the tests window to narrow down your list of projects. Simply enter '*.Tests' and all non-test projects will be removed from the view.
Cheers,
Remco