Add optional toolbar field to quickly change course

[joonashak]

I would love to have the option of having a drop-down menu in the NetBeans toolbar for quickly changing between (active) courses in TMC. Probably shouldn't be there always (and not by default?) since surely a lot of users take only one course that uses TMC at a time.

[joonashak]

Also, it would be nice to be able to select different exercise folders for different courses. But that should probably be another issue..?

[Redande]

Courses actually have separate folders under your NetBeansProjects folder.

The dropdown menu for faster course swapping is a good idea!