Can’t help thinking that this would be better off as an iOS application. You could put your iPad or iPhone on a music stand and off you go. A phone would certainly make for a convenient note-book size reference screen.
I know that on the rare occasions I get my guitar out, the last place I’ll be is at my desk where my desktop machine is, and certainly where I am more likely to be, there’s nowhere safe or convenient to put my MBP.
I’ve been thinking about doing an IOS version, partly for the reason you give, and also because there’s a wider user base. Fretspace started out on the Mac because I’m a Mac programmer and because the Mac interface is more suited to creative programs. It’s certainly possible that Fretspace (or parts of Fretspace, such as the chord and scale pickers) could be converted to an IOS interface. I generally print charts that I’m working with, rather than have a computer nearby, but an iPhone or iPad would be a paperless alternative.
When I’m creating charts, or working with any other kind of document, I’d much rather do that on a computer than a phone.