I strongly doubt that an AppKit replacement would fix the sandbox issues. Also, to be fair, I think that quality of the sandbox has improved significantly over

I strongly doubt that an AppKit replacement would fix the sandbox issues. Also, to be fair, I think that quality of the sandbox has improved significantly over the years. The remaining issues are in general pretty rare (my apps have thousands of users, and I only get a handful of support requests about these issues per year). The problem is that when these issues pop up, there is nothing I can do to debug them -- aside from asking users "have you tried rebooting your computer?" (which does fix the issues occasionally) Apple really needs to make better error reporting. When opening a security scoped bookmark fails, the system should return a proper error message, or at least log the reason for the failure. And they must absolutely fix their error messages. When the sandbox denies access to a file, AppKit shouldn't suggest changing permissions in the Finder -- that won't help a thing.