Dealing with suspended applications

[koekeishiya]

Sort of related to #599, but this is a more general problem. In short, the issue is that the AX API is blocking. If we try to interact with an application that is currently suspended, we will halt until the AX API times out (currently set to 1 second).

The main issues are:

1. If an application is suspended when yabai is launched, we are unable to observe this application and it will go untracked until the application is restarted, or yabai is restarted after the application has become responsive. This could potentially also happen if the application becomes unresponsive during or shortly after startup, before yabai is able to subscribe to notifications.

2. If an application becomes unresponsive mid-session, and we try to interact with it in any way (get windows, move a window, etc.), it will block and the request will silently fail.

Issue 1. can more or less be solved by deferring the initialization of unresponsive applications til they report back as being responsive.

Issue 2. is tricky and there are many different ways to approach this, but none are really all that great.

[koekeishiya]

A solution for issue 1. has been implemented https:/koekeishiya/yabai/tree/track-unresponsive, but I want to give this a more thorough analysis before any change is made, and I think it is a bad decision to mix this in with the other ongoing changes that are currently being scheduled for the next release.