Attn @jenshnielsen...

Happy with the change, but I'm not claiming any expertise on the topic.

OK, figured out how to pass the failure up the line. Now lazy_init calles check_framework after the app has started...

... and doesnt' depend on the deprecated calls...

The problem is that for backend fallback to correctly work, we need importing the backend to fail with ImportError; backend fallback (at least as it is written right now) doesn't work with later failures.
So I think right now using the deprecated Carbon API remains the best solution that we know of.

OK - see my comment on gitter - it turns out that not having the Framework installed (pythonw) doesn't stop the GUI from working FAICT, it just is slightly suboptimal in that the GUI doesn't have a dock icon, so it can get burried under other windows. To my taste that isnt' something to Error over, but rather we could/should throw a warning.

Well, you have to ask those who put in the check to start with (#1613 and other PRs).
(Let's keep the discussion here rather than on gitter.)

Ah, OK, the issue is #665; if you open the save dialog you can't get typing focus in the dialog box. I'm 50/50 still if that requires us to error or warn, but it can be said to be not fully functional.

@jklymak Afaik we put this in because we got so many errors and spent so much time tracking down why the gui was not working. With pyqt5 and wxpython being pip installable now it seems easier for users to switch to a functioning backend rather than using a semi broken one so I am mildly in favor of erroring out but warnings are fine with me too.

OK, let's try something else.
In the pre-OSX10.6 code, only GetCurrentProcess and SetFrontProcess are deprecated (https://developer.apple.com/documentation/applicationservices/1501115-getcurrentprocess?language=occ); CGMainDisplayID is not (https://developer.apple.com/documentation/coregraphics/1455620-cgmaindisplayid). Would we be lucky enough to have CGMainDisplayID() return 0 on non-framework and nonzero on framework builds, in which case that'd be a way to check for frameworkness?

Would we be lucky enough to have CGMainDisplayID() return 0 on non-framework and nonzero on framework builds,

Nope, that doesn't work. Newest push just uses the deprecated methods at import.

Merging this as it un-breaks osx for now (and pushing the reckoning of using deprecated APIs to future us).

The OSX backend is now agg based like the others (rather than an alternate rendering path) and presumably should also be made to play nice with cairo. The biggest advantage of the OSX backend over tk/wx is that it support hi-dpi. The biggest advantage over Qt is that it is no extra dependencies (on macs).