I have not had any software hard crash my computer like this in years. Avoid it at all costs. I almost lost hours and hours of work, but fortunately had saved just before installing xscope.
The program is a complete mess. The idea is good, but that doesn’t make up for the horrible operation.
The overlay feature is a joke. It doesn’t work. It complains that a normally sized browser window is too large, and it wants you to resize it down to a tiny square. That means that the overlay has to be placed on a completely useless, tiny web page. It’s idiotic.
The auto-measure feature is very glitchy. It has a really hard time figuring out the boundary of the image you’re trying to measure. It would be much more useful if it had intuitive manual controls.
The on-screen help is also very badly designed. It was nearly impossible to understand the installation instructions for the overlay feature. The help screen also opens unexpectedly and blocks what you’re working on. How am I supposed to measure things on my screen with the “help” screen covering 2/3 of it?
The installation of the dysfunctional overlay feature is a complete kludge. You have to open Security and Privacy settings and give the program control over operations of the computer! You’re breaking the sandboxing that is a key security mechanism on the Mac, and this is likely why the crash of xscope brought down the entire computer.
Avoid this thing unless you enjoy losing data, corrupting your storage, and wasting a lot of time.