Public bug reported:
I am reporting a Wacom tablet input problem affecting classic GTK2/X11
applications running through XWayland on Ubuntu 26.04.
My system uses Ubuntu 26.04 with a Wayland session and XWayland 24.1.10. The
tablet is a Wacom CTL-472 One by Wacom (S), USB ID 056a:037a.
The Wacom tablet works correctly at the kernel input level. evtest detects the
tablet and reports pen position, pressure, proximity, and button events.
XWayland also detects the tablet correctly. xinput lists the device as
xwayland-tablet stylus:16, with absolute X and Y coordinates, pressure, tilt
and other tablet valuators. xinput test also shows pen motion, button press and
release, and changing pressure values.
GTK3 applications receive the Wacom events correctly. However, classic GTK2
applications such as Xournal 0.4.8 did not receive the Wacom pen input. The
Xournal application itself recognized the XWayland tablet device and had XInput
enabled, but pen button and motion events did not reach the GTK2 application.
I traced the problem to the interaction between the legacy GTK2 XInput handling
and XWayland.
The installed XWayland version was 2:24.1.10-1. I obtained the Ubuntu source
package and rebuilt XWayland after making a one-line change in
hw/xwayland/xwayland-input.c.
In the function sprite_check_lost_focus(), the following return statement was
changed from "return !pointer_crossing;" to "return FALSE;".
After rebuilding and installing the patched XWayland package, I restarted the
Wayland session and tested Xournal again. The Wacom pen then worked correctly
in Xournal, including writing with the pen.
The change is a minimal one-line patch to XWayland 24.1.10. The locally rebuilt
package was xwayland version 2:24.1.10-1.
This appears to correspond to the upstream XWayland fix for tablet tools no
longer working as slave devices.
I have retained the locally built package and the exact source patch for
testing or reproduction.
The issue can therefore be reproduced as follows: use Ubuntu 26.04 with Wayland
and XWayland 24.1.10, run a legacy GTK2/X11 application such as Xournal, and
use a Wacom CTL-472 tablet. The tablet is visible through XWayland/XInput, but
the GTK2 application does not receive the pen input. Applying the one-line
change described above restores tablet input.
** Affects: xwayland (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2169242
Title:
Wacom tablet input broken in GTK2/XInput applications with XWayland
24.1.10, and the fix for the bug
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