C-g doesn't work in EXWM buffers

[walseb]

Hello!

The C-g key is useful for when you something causes Emacs to hang.

It seems, currently in EXWM, the C-g key isn't forwarded to Emacs while it's busy, even when it's in the prefix keys.

Here's how to reproduce it.

Put this in your config to ensure EXWM allows C-g through:

(setopt exwm-input-prefix-keys
        '(
          ;; C-g
          7
          ))

1. Open any EXWM buffer
2. Type M-x eval-expression RET
3. Type (sleep-for 10)
4. Type C-g

You should now have to wait for the entire 10 seconds for Emacs to unblock.

quit should be shown in the minibuffer, which is the C-g you ran in step 4 being executed late.

Try it in a normal buffer, and pressing C-g should cancel the sleep right away.

Thoughts?

[Stebalien]

This should be fixable. Currently, when you "pass through" C-g, it gets pushed onto Emacs's internal event queue and won't be processed till sleep-for exits.

I can't find a way to eagerly process commands but we can modify the input handler to:

1. Detect C-g. Or whatever the quit key happens to be: (nth 3 (current-input-mode)).
2. Set quit-flag to t.

We'll need to make this behavior customizable.

We'll also likely want to wrap the entire input handling loop in an inhibit-quit block to ensure that this flag doesn't take effect till we're all done.