Fix gesture preview crash on macOS 12

[aaronkollasch]

[NSView lockFocus] was deprecated in macOS 10.14 and seems to be removed on 12.0.
This PR prevents the prefpane from crashing while trying to show the gesture preview window. It uses a single background color as a substitute for a drawn background, though it is not as pretty.
imageWithSize:flipped:drawingHandler is a potential replacement for lockFocus, e.g.

NSImage *bg = [NSImage imageWithSize:[self frame].size
                                 flipped:NO
                          drawingHandler:???];

(Sorry for the several pull requests. I could merge them into an M1+macOS 12 PR, but they seemed like separate issues. Just submitting in case they are helpful to anyone else.)

[we11adam]

As much as I appreciate @sukolsak's original work on Jitouch, I don't think he's interested in maintaining this project any more, because Jitouch haven't received a single update on its official website for almost three years and this github repo doesn't look active neither. @aaronkollasch Could you please consider taking on the work and releasing compiled artifacts in you own repo? Thanks.

[aaronkollasch]

@we11adam I'll consider it if I have time. However, I don't have an Apple Developer signing certificate and I'm not sure it will be worth the expense.

There is the message on the website when clicking on the free license key that says:

We still plan to support our users, and we're looking forward to releasing the next jitouch 3.0.

@sukolsak @supasorn are you still planning on releasing jitouch 3.0?

[aaronkollasch]

Ok @we11adam, given I haven't heard from the original authors I've released compiled artifacts:
https://github.com/aaronkollasch/jitouch/releases/latest
Feel free to submit issues to my repository if you encounter any!

[we11adam]

Ok @we11adam, given I haven't heard from the original authors I've released compiled artifacts: https://github.com/aaronkollasch/jitouch/releases/latest Feel free to submit issues to my repository if you encounter any!

@aaronkollasch Hi Aaron, thanks for actively maintaining the forked version. 2.79 works great on my MacBook. Really appreciate it!

[Crazor]

As much as I appreciate @sukolsak's original work on Jitouch, I don't think he's interested in maintaining this project any more, because Jitouch haven't received a single update on its official website for almost three years and this github repo doesn't look active neither.

Just wanted to let you know that stuff's going on behind the scenes, and there will indeed be a new release coming up. I've already involved Aaron to merge his changes, but my work isn't quite ready yet. So keep your eyes peeled and use Aaron's build for the time being!

[we11adam]

@Crazor Hi, care to share some progress here? I'm not being pushy, just really curious. Take your time. Thank you! :)