Modifier keys like Shift, Ctrl, Alt don't always work under XWayland

[bk138]

Bug behaviour

Modifier keys like Shift, Ctrl, Alt only work when Gromit-MPX is toggled on over other XWayland windows, but are ignored for drawing over pure Wayland windows. For instance, when toggled over an xterm, all works, but over a gnome-terminal, it does not.

Things tried so far

• looks good, but is for wayland, not xwayland:

  • https://git.eclipse.org/r/c/platform/eclipse.platform.swt/+/96061/
  • https://git.eclipse.org/c/platform/eclipse.platform.swt.git/commit/?id=d674cf3686c90551f3006ba4e55f1fd66f77658c
  • also: https://git.eclipse.org/c/platform/eclipse.platform.swt.git/commit/?id=467296f8e2b8352bd93e9bc7039f9c232e18bee0

• ask modifiert state from slave device? -> ⛔

• gtk_window_new (GTK_WINDOW_TOPLEVEL); instead of gtk_window_new (GTK_WINDOW_POPUP); and set stay-on-top and set sticky?

  • with X11 session: still goes to background, sticky also not working
  • same under wayland with xwayland
  • -> ⛔

• look into GKD_WINDOW_TEMP, which is used for gtk_window_new (GTK_WINDOW_POPUP);

  • there is no special xwayland handling in GTK/GDK -> ⛔

• difference between X11 session and Wayland session using XWayland is that the latter is rootless. Might this be the reason? Can we maybe set an additional property to our GTK_WINDOW_POPUP so that it eats modifier events as well in that case?

  • https://stackoverflow.com/questions/39087079/detect-modifier-key-release-in-x11-root-window

• have a look at xcape features (double bind modifiers) swaywm/sway#719

• https://stackoverflow.com/questions/1925568/how-to-give-keyboard-focus-to-a-pop-up-gtk-window

• xwayland keyboard grabs? --> https://unix.stackexchange.com/a/607473/80396 and https://gitlab.com/Remmina/Remmina/-/issues/2106 -> hmm well no, that seems for grabbing the whole keyboard with XGrabKeyboard(), not XGrabKey() ⛔

[TRPB]

As a workaround, would it be possible to have a command line option that starts drawing? E.g.

gromit-mpx --draw

That way I can bind F9 im my desktop environment to run that command.

One option would be registering global shortcuts in the desktop environment itself, but I have no idea if there is a standard way of doing this that wouldn't involve different code for kde/gnome/etc.

[bk138]

As a workaround, would it be possible to have a command line option that starts drawing? E.g.

gromit-mpx --draw

That way I can bind F9 im my desktop environment to run that command.

One option would be registering global shortcuts in the desktop environment itself, but I have no idea if there is a standard way of doing this that wouldn't involve different code for kde/gnome/etc.

What you mention has already been tackled in #27 with 6501486 - this here is about the modifier keys only.

[vipseixas]

Is there any workaround for this problem?

If not, is it possible to put a "default tool" selection in the menu?

[jgrocha]

Modifiers are working here, on Wayland, Ubuntu 24.10, GNOME Shell 47.0, gromit 20041213-9build3, nvidia-driver-560

The problem here is the hotkey. I have to open the About box and have it in focus to use F9 to start and end draw mode.

If the About closes (captures ESC, for example), I can not leave the draw mode. Should I open a new issue? Should I add this to #27?

[bk138]

@jgrocha modifier keys do work for X11 windows (of which Gromit-MPX is one), not for pure Wayland windows. If the hotkey does not work under GNOME for you, please open a new issue, yes. (Please indicate how you start Gromit-MPX.)

[jgrocha]

@jgrocha modifier keys do work for X11 windows (of which Gromit-MPX is one), not for pure Wayland windows. If the hotkey does not work under GNOME for you, please open a new issue, yes. (Please indicate how you start Gromit-MPX.)

Isn't gnome-terminal a wayland window? I've tested with xprop and it seems to me that gnome-terminal is a wayland window. The modifiers work on top of that window. But maybe I'm missing something. I'm not an expert.

Edit: the issue is: "...don't always work". Sometimes they work :-)

[jgrocha]

I've compiled Gromit-mpx with the last git version (now 1.7 instead of 1.4).
The hotkey works well in 1.7, but the modifiers don't as described.
@bk138 Sorry for the noise.