So, because I can't resist any new audio toy, I downloaded it and tried it...it locked up X, or the desktop or something, on Fedora 21. Which seems odd, as it's using tk for the interface, which ought to be old and stable, by now. But, maybe nobody is testing current desktops against tk anymore, so bugs don't get found.
Also, the color scheme in the screenshots is really the color scheme; it's not just botched screenshots. Completely unreadable, for me, at any reasonable distance from my monitor. I mean, I understand I'm not so young and my eyesight has never been great, but I can't believe this is a comfortable level of contrast for anyone. Hopefully this is easily configurable.
There was a relatively recent bug in X11 which would cause X to crash when any arcs were drawn on screen with certain beginning/ending angles. This might be what's affecting you at the moment.
A yum update and reboot allowed it to work. You're likely right (or it was some other Xorg bug). Getting color scheme readable was easy (making it look nice and be readable will take a lot more work).
It feels pretty complex, and it seems like it's heavily reliant on hotkeys to be able to do much of anything quickly/easily. I recall being very effective at getting ideas working on hotkey based trackers in the distant past, but it's been a long time, and I dunno if I have the patience to learn enough of it to be productive even approaching the level I'm productive on other tools. It almost feels like Impulse Tracker is its ideological ancestor, in its reliance on keyboard navigation. Which some folks love. I'm not necessarily in that camp these days.
But, still an interesting experiment and UI design for music.
Also, the color scheme in the screenshots is really the color scheme; it's not just botched screenshots. Completely unreadable, for me, at any reasonable distance from my monitor. I mean, I understand I'm not so young and my eyesight has never been great, but I can't believe this is a comfortable level of contrast for anyone. Hopefully this is easily configurable.