Keyboard key is falsely recognized as being pressed

[m-rey]

steps to reproduce

1. open two kitty terminals, side by side
2. move your mouse over the first terminal, focusing it
3. hold down a keyboard key
4. while still pressing the key, move the mouse away from first terminal to second terminal, focusing the second terminal
5. release the key while being in the second terminal. Now no key is currently being pressed
6. move the mouse back to the first terminal, focusing it
   -> the previously held down key is being printed and thus recognized as pressed, even though no key is being pressed.

[kovidgoyal]

I cannot replicate on X11 using those steps with

kitty --config NONE -o focus_follows_mouse=y

[Luflosi]

I cannot replicate on macOS with the same command line options.

[m-rey]

using swaywm (wayland), kitty 0.14.4 with
kitty --config NONE -o focus_follows_mouse=y

[kovidgoyal]

Ah Wayland. Yeah that is a limitation of Wayland's design. In
Wayland there are no key repeat events. So glfw runs a timer to
simulate key repeat. If you release the key on another window then there
is never a release event to stop the timer in the first window. And so
it keeps going. I suppose one could workaround it by also killing the
timer when the window loses focus, but then that means you cannot mouse out
and mouse back with a key pressed and expect the repeat to continue.

[kovidgoyal]

@emersion any hints on what the correct way to do this in wayland is, if there even is one?

[agraul]

@kovidgoyal GNOME Terminal seems to "kill the timer" (or however it does it), it does not continue with the input in either case (lose focus and keep button pressed / lose focus and stop pressing key)

[kovidgoyal]

yeah killing the timer on focus loss is the obvious thing to do, but it means that if you keep a key pressed and your mouse happens to stray off the window for a second, boom key repeating stops working. This does not happen on other platforms. So I would hope wayland has some way to actually implement it correctly as is done on all other platforms, but maybe I am being optimistic.

[emersion]

If you release the key on another window then there
is never a release event to stop the timer in the first window.

Clients should release all keys when the wl_keyboard.leave event is sent.

[kovidgoyal]

On Mon, Sep 30, 2019 at 04:06:52AM -0700, Simon Ser wrote: >If you release the key on another window then there is never a release event to stop the timer in the first window. Clients should release all keys when the `wl_keyboard.leave` event is sent.

I guess that means, if your mouse strays off the window accidentally and you have focus_follows_mouse, key repeat is going to stop on Wayland, unlike all other platforms.

[emersion]

No, it will work, just like on other platforms.

If you have focus_follows_mouse and move the mouse accidentally, it'll change the keyboard focus, just like on X11.

[kovidgoyal]

On Mon, Sep 30, 2019 at 04:15:34AM -0700, Simon Ser wrote: No, it will work, just like on other platforms. If you have focus_follows_mouse and move the mouse accidentally, it'll change the keyboard focus, just like on X11.

See above. On X11 with focus_fllows_mouse you can move the keyboard to another window and move it back and the repeat events will continue. Same on macOS. Only on wayland will that scenario cause them to stop.

[emersion]

The wl_keyboard.enter event contains the set of pressed keys. You can restart the timers there.

[kovidgoyal]

On Mon, Sep 30, 2019 at 05:30:50AM -0700, Simon Ser wrote: The `wl_keyboard.enter` event contains the set of pressed keys. You can restart the timers there.

Interesting, thanks. I can use that to check if the key being repeated is still pressed and restart timer accordingly.