Using OS X 10.11.1 El Capitan, sometimes I'm confronted with a 'nonresponsive window': a program that keeps stalling for like 10-30 seconds. In most cases this happens to be Adobe Photoshop, but I've encountered it with other programs as well (e.g. Firefox or Chrome).
Note that the program isn't completely frozen or cashed, it's just doing some heavy calculations or whatever, and the window doesn't respond (I can't click or drag it) but eventually it comes back to life and continues working normally.
I can reproduce it, for example by having a very large image open in Photoshop and then going File > Save for Web.
While this is happening, I get the spinning color wheel, and I can't bring other program windows to the front. For example if Photoshop is stalling, I would like to cmd+tab to my browser or whatever and do something else there. But that doesn't work, the stuck Photoshop window remains in front of any other program I switch to.
Is there a way to hide or minimize such a program in OS X, so I can continue to work in others while this particular thing does whatever it needs to do?
Note that I do NOT want to force quit or kill a program, it need to keep running, it just needs to do so in the background, allowing me to use other programs meanwhile.
Edit: Cmd ⌘ Tab ⇥ still works, but Photoshop will not drop to the background whilst busy, as in this illustration…
Best Answer
I'm tempted to post this as an answer, even without full info…
I am assuming that if you cannot Cmd ⌘ Tab ⇥ to another app at this point, it is because the entire machine is currently too busy to respond, not just the frontmost app.
If an app itself is unresponsive [& you can see other apps around/behind it, i.e. not full screen or maximised], you ought to be able to simply move the cursor outside that unresponsive app & the daisy wheel will go away, returning to the standard cursor. Clicking one of the other apps will bring it to the front. Cmd ⌘ Tab ⇥ at this point would also work.
If the daisy wheel doesn't go away outside the borders of the unresponsive app, then the entire machine is too busy to respond - usually just temporarily, until whatever process taking all the resources has finished its task.
Photoshop processing a very large image for the web is just the kind of task that can temporarily use large amounts of RAM & CPU. I just tested on a 5000 x 3000 image. Photoshop went busy for approx 15s, RAM usage doubled & CPU usage went to 100% [which is 1/24th of the number of virtual cores I have, so in essence used one core to its fullest] . I was able to change screens, switch to other apps etc, but I'm running on a 12-core Mac Pro with 64GB RAM.
From this snapshot you can see the brief effect [highlighted in red] on the cores & the drop to 'not responding' in Activity Monitor.
Perhaps try some comparison tests & see what figures you get at the same point.