Describe the Bug
On Linux (Flatpak build), a graphics tablet's pen click does not register in the desktop app's CEF-rendered UI or viewport when OpenTabletDriver is configured in Absolute mode (normal tablet-to-screen 1:1 mapping), even though:
- The exact same tablet/pen works correctly in the web version at https://editor.graphite.art/ (in Chromium), also in Absolute mode
- A physical USB mouse clicks normally in the desktop app
xdotool click 1 (synthetic XTEST click) also fails to register in the desktop app- Switching OpenTabletDriver to Relative mode makes clicking work correctly in the desktop app — this isolates the bug to something specific about how absolute-positioning tablet devices are handled, since relative mode is otherwise unusable for real drawing (no 1:1 tablet-to-screen mapping)
Cursor motion from the tablet works perfectly in Absolute mode in the desktop app — only button press/release events fail to have any effect while in that mode.
Environment
- OS: Void Linux, X11 (picom compositor, XFCE)
- Graphite: desktop Flatpak build (
art.graphite.Graphite), downloaded ~July 2026
- Tablet driver: OpenTabletDriver 0.6.7 (Flatpak)
- Tablet: Huion H1161
- GPU: AMD (RADV/Mesa)
Steps To Reproduce
- Install OpenTabletDriver via Flatpak, configure tablet in Absolute mode ("Artist Mode" preset) with tip bound to Mouse Button: Left
- Install Graphite via Flatpak
- Launch Graphite desktop app
- Attempt to click/draw with the stylus tip on the canvas or any UI button
- Motion works; the click has no effect
- Switch OpenTabletDriver to Relative mode, click Apply, retest — clicking now works correctly
Investigation so far
xinput test-xi2 confirms the pen's ButtonPress/ButtonRelease arrive as genuine X11 core-protocol events from the same device (OpenTabletDriver Virtual Tablet, XI2 id 19) that generates the working motion events — not routed through the XTEST virtual pointer (id 4)udevadm info confirms the OTD virtual device is tagged ID_INPUT_MOUSE=1libinput list-devices shows the OTD virtual device's Capabilities: pointer, but its DeviceChanged XI2 announcement in Absolute mode includes absolute X/Y valuators plus an XIScrollClass (relative horizontal/vertical scroll valuators) — attributes a plain mouse does not have- A real physical USB mouse (no absolute valuators, no scroll-class) clicks Graphite's UI/canvas without any issue in either mode
xdotool click 1 (XTEST-injected click) also fails silently in the desktop app while in Absolute mode- Confirmed: switching the same physical tablet/driver to Relative mode (removing absolute valuators from the device's XI2 announcement) makes clicks work correctly again
This strongly suggests Graphite's CEF-embedded input handling (see #2535, the CEF-based desktop architecture) filters or mis-routes button events specifically from devices that report absolute positioning valuators, rather than a general click-handling bug — since motion, physical mouse clicks, and relative-mode tablet clicks all work fine, and only absolute-mode tablet clicks fail.
Additional Details
- Toggling Preferences → Render GUI on CPU (
disable_ui_acceleration in preferences.ron) fixed an unrelated issue where the GUI failed to render at all, but did not affect this click bug.
- Happy to provide further logs/testing (e.g.
libinput debug-events, CEF verbose logging flags) if useful for triage.
Describe the Bug
On Linux (Flatpak build), a graphics tablet's pen click does not register in the desktop app's CEF-rendered UI or viewport when OpenTabletDriver is configured in Absolute mode (normal tablet-to-screen 1:1 mapping), even though:
xdotool click 1(synthetic XTEST click) also fails to register in the desktop appCursor motion from the tablet works perfectly in Absolute mode in the desktop app — only button press/release events fail to have any effect while in that mode.
Environment
art.graphite.Graphite), downloaded ~July 2026Steps To Reproduce
Investigation so far
xinput test-xi2confirms the pen'sButtonPress/ButtonReleasearrive as genuine X11 core-protocol events from the same device (OpenTabletDriver Virtual Tablet, XI2 id 19) that generates the working motion events — not routed through the XTEST virtual pointer (id 4)udevadm infoconfirms the OTD virtual device is taggedID_INPUT_MOUSE=1libinput list-devicesshows the OTD virtual device'sCapabilities: pointer, but itsDeviceChangedXI2 announcement in Absolute mode includes absolute X/Y valuators plus an XIScrollClass (relative horizontal/vertical scroll valuators) — attributes a plain mouse does not havexdotool click 1(XTEST-injected click) also fails silently in the desktop app while in Absolute modeThis strongly suggests Graphite's CEF-embedded input handling (see #2535, the CEF-based desktop architecture) filters or mis-routes button events specifically from devices that report absolute positioning valuators, rather than a general click-handling bug — since motion, physical mouse clicks, and relative-mode tablet clicks all work fine, and only absolute-mode tablet clicks fail.
Additional Details
disable_ui_accelerationinpreferences.ron) fixed an unrelated issue where the GUI failed to render at all, but did not affect this click bug.libinput debug-events, CEF verbose logging flags) if useful for triage.