Crop handles sometimes not visible

Is there an existing issue for this?

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

Describe the bug

When selecting the crop module, sometimes the crop handles and outline do not appear even when the mouse is moved over the image. Nonetheless they are active and if I click and drag where the handles should be, not only do they apparently move (remaining invisible), but the live coordinate values change accordingly on the crop module panel. Deselecting the crop module at that point crops the image as expected, and the next attempt at cropping always works as expected.

I have tried to move to the next image and activate the crop module quickly, assuming it might be a race condition. I have also tried making a crop as the first step in editing an image, as well as after rotation or exposure, but it seems to make no difference. I cannot force it to happen, and it seems to occur about 1 in every 30-40 images. It does seem to occur more often after the app has been open and idle for an extended period. When I left to run an errand, the app was open for an hour or so, and the error occurred immediately when I came back and edited the next image.

Steps to reproduce

1. Select crop module by clicking on it or tapping the shortcut key.
2. Crop handles do not appear (rare).
3. Move mouse into corner of image and click/drag.
4. Crop module live coordinate display updates as mouse is moved.
5. Move crop handles to arbitrary locations.
6. Deselect crop module.
7. Image is cropped according to the position of the crop handles.
8. Next attempt at cropping seems to work as expected.

Expected behavior

Expect crop handles to appear after the crop module is enabled/selected and the mouse is moved over the image area.

Logfile | Screenshot | Screencast

I had to run the program for over an hour before it gave the error, so apologies for the long log file. Error should be very near the end but I didn't want to accidentally remove pertinent info related to the workflow.

darktable.log.zip

Commit

I did not notice this before the 5.5.0 nightly releases, although it may have just been much less common.

Where did you obtain darktable from?

darktable.org / GitHub release

darktable version

Produced on 5.5.0+1465~g29338e8068

What OS are you using?

Mac

What is the version of your OS?

Sequoia 15.7.7 (24G720)

Describe your system

Mac M1 Ultra (2022), 64GB

Are you using OpenCL GPU in darktable?

Yes

If yes, what is the GPU card and driver?

M1 built-in GPU system

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

Due to the seeming random nature of this issue it took a while to reproduce. I can say that I left the app open and idle for about an hour before coming back to it - whereupon the crop handle error occurred immediately on my next edit.

Start by reproducing the crop workflow, especially after leaving the app idle, and inspect the attached darktable.log.zip near the reported failure. Trace why the crop handles and outline remain invisible while coordinates still update; done means the handles reliably appear and the crop is applied correctly on the first attempt.