I was a bit confused how tabs work in the IDE so I did a bit of testing. Could someone please confirm my findings?
You can create new tabs with the right arrow. This creates a new file inside the project directory. Or you can use 'Add file...' which will create a copy of an existing file in the directory.
All files are compiled together into one program.
The main use as I see it is to clean up the 'main' tab. Functions can be grouped together in their own tabs ('digital IO', 'serial IO',...) and be called from the loop().
Am I right? Did I miss something?