Darktable crashes on macOS when trying to enter full-screen mode or open second Darkroom image window

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

Possibly related to #19540 (inactive).

Darktable immediately crashes when I try to either (1) enter full-screen mode or (2) "Display a second Darkroom image window". I am on macOS Tahoe 26.3 and I observe this bug in both Darktable 5.4.1 and the latest nightly build.

Steps to reproduce

Darktable immediately crashes when I either (1) try to enter full-screen mode by clicking the green button at the upper-left corner of the window, or (2) try to "Display a second Darkroom image window" by clicking the bottom-left icon in Darkroom view.

The full-screen mode bug appears to only occur when I am in Darkroom view. When I click the full-screen green button and I'm inside Lighttable, full-screen mode is enabled without any issues.

I was also just able to reproduce the instant-crash by (1) entering full-screen from within Lighttable (clicking green button on upper-left corner of the window), (2) switching to Darkroom view, then (3) exiting full-screen mode by hitting Escape or clicking the green button again.

I have tried a couple things to fix the error (disabling "Assign To...This Desktop" from the dock, disabling OpenCL mode) but nothing has worked so far.

Expected behavior

No crash :')

Logfile | Screenshot | Screencast

Have attached two "Problem reports" shown after Darktable crashes: One after trying to enter full-screen mode, the other after trying to display a second Darkroom image window.

report_darktable-fullscreen-mode.txt
report_darkroom-image-window.txt

Commit

No response

Where did you obtain darktable from?

darktable.org / GitHub release

darktable version

5.5.0+995~gc3afa02829

What OS are you using?

Mac

What is the version of your OS?

MacOS Tahoe 26.3

Describe your system

Command system_profiler SPHardwareDataType output:

Hardware:

    Hardware Overview:

      Model Name: MacBook Pro
      Model Identifier: MacBookPro18,1
      Model Number: MK193LL/A
      Chip: Apple M1 Pro
      Total Number of Cores: 10 (8 Performance and 2 Efficiency)
      Memory: 16 GB
      System Firmware Version: 13822.81.10
      OS Loader Version: 13822.81.10
      Serial Number (system): G6G62TVPJ1
      Hardware UUID: E882C338-B8C2-5DDB-AB00-B2665E5831C2
      Provisioning UDID: 00006000-0016288C22D2801E
      Activation Lock Status: Disabled

Are you using OpenCL GPU in darktable?

No

If yes, what is the GPU card and driver?

No response

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response

Start by reproducing the crash through the Darkroom full-screen and second-image-window controls, including the Lighttable-to-Darkroom full-screen transition. Compare report_darktable-fullscreen-mode.txt and report_darkroom-image-window.txt, then trace the relevant macOS window handling. Done means both workflows work without crashing on the reported macOS setup.