** Description changed:
+ [ Impact ]
+
Upstream issue: https://gitlab.gnome.org/GNOME/gtk/-/issues/7515
- Touchscreens are under "Virtual core pointer" virtual device in X11, and
the virtual device is recognized as a `GDK_SOURCE_MOUSE`.
- in `gdk/x11/gdk/x11/gdkdevicemanager-xi2.c`, `gdk_touch_event_new` is
passed with the virtual device.
- There are many places that checks whether the event is from touchscreen or
mouse, by using `gdk_device_get_source` on the device included in the event
above, which is `GDK_SOURCE_MOUSE` despite a touchscreen physical device is
used.
This issue caused bugs for LP: #2051886 and LP: #2119065, as they
interpret touchscreen input as mouse events, and expect it to input like
a mouse.
- A ubuntu-bug report will be submitted later
+ [ Test Plan ]
+
+ 0. Obtain a machine with a touchscreen
+ 1. Log in to Ubuntu (on Xorg)
+ 2. Run `GDK_DEBUG=input nautilus`
+ 3. Verify in the terminal output that there exists an input device matching:
+ """
+ input device:
+ name: Virtual core pointer
+ type: logical
+ source: direct touch
+ """
+
+ 4. Open the debug console with Ctrl+Alt+D
+ 5. Navigate to Recorder
+ 6. Click the "Record frames" button
+ 7. Focus nautilus
+ 8. Click anywhere
+ 9. Switch back to the recorder window
+ 10. Select the "Touch Begin" event
+ 11. Verify that it originates from a device named "Virtual core pointer touch"
+
+ [ Regression Test Plan ]
+
+ Install and test gtk4-demo (from the gtk-4-examples package) as well as
+ a few other GTK/GNOME applications like nautilus and gnome-text-editor,
+ and verify that they continue to launch and work as expected without
+
+ [ Where problems could occur ]
+
+ The patch only affects X11 and couldn't possibly regress Wayland.
+ The patch affects general input handling in GTK4, so a regression test plan
is included to ensure that GTK applications still behave as expected.
+
---
ProblemType: Bug
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
CasperMD5CheckMismatches: ./.disk/casper-uuid-oem ./casper/initrd
./casper/minimal.standard.live.hotfix.size ./casper/minimal.standard.live.size
./casper/minimal.manifest ./casper/minimal.standard.manifest
./casper/minimal.standard.size ./casper/minimal.hotfix.size
./casper/minimal.standard.live.hotfix.squashfs
./casper/minimal.standard.hotfix.squashfs ./casper/minimal.standard.hotfix.size
./casper/minimal.hotfix.squashfs ./casper/minimal.standard.live.manifest
./casper/minimal.size ./boot/grub/grub.cfg
CasperMD5CheckResult: fail
CurrentDesktop: ubuntu:GNOME
DistributionChannelDescriptor:
# This is the distribution channel descriptor for Ubuntu 24.04 for Dell
# For more information see
http://wiki.ubuntu.com/DistributionChannelDescriptor
canonical-oem-somerville-noble-oem-24.04b-20250714-538
DistroRelease: Ubuntu 24.04
InstallationDate: Installed on 2025-07-15 (15 days ago)
InstallationMedia: Ubuntu OEM 24.04.2 LTS "Noble Numbat" - Release amd64
(20250714)
Package: libgtk-4-1 4.14.5+ds-0ubuntu0.1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 6.11.0-1025.25-oem 6.11.11
Tags: noble
Uname: Linux 6.11.0-1025-oem x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sudo users
_MarkForUpload: True
** Also affects: gtk4 (Ubuntu Plucky)
Importance: Undecided
Status: New
** Changed in: gtk4 (Ubuntu Plucky)
Status: New => In Progress
** Changed in: gtk4 (Ubuntu Noble)
Status: Triaged => In Progress
** Changed in: gtk4 (Ubuntu Plucky)
Importance: Undecided => Low
** Changed in: gtk4 (Ubuntu Plucky)
Assignee: (unassigned) => Alessandro Astone (aleasto)
** Changed in: gtk4 (Ubuntu Plucky)
Milestone: None => plucky-updates
--
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https://bugs.launchpad.net/bugs/2119066
Title:
X11 touchscreen events are handled as mouse events
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