I am having another of my occasional usability problems. It is, again, something in the GUI that I have fumble fingered. Anyway, in the darkroom, I can successfully create a snapshot, and it shows in the list of snapshots. However, there is no “split line” shown, and no control to drag it back and forth to compare two states of the editing progress.
I have consulted the darktable user manual and it mentions no possibility of hiding or turning off the split line. How do I get it back?
It’s possible to drag the line outside the image. Perhaps that’s what happened. Simply clicking somewhere on the image should bring it back, if that’s the case.
Thanks. I had tried that, and I just now tried it again. It doesn’t bring it back.
Oh, PS - If it makes any difference, I am running Arch Linux and darktable 5.0.1 from the Arch Linux package repository.
Have you definitely selected the snapshot in the snapshots module? Do you have any modules active that also overlay stuff on the image (e.g. global color picker, drawn masks)?
If you can screen record your steps from starting darktable up to the point you activate the snapshot, it might give us some clues?
Well, I must be a dunce. Selecting the snapshot does the trick. I wonder why the docs don’t say anything about that.
Thank you.
They do. See the fourth paragraph of the following page: darktable user manual - snapshots
Oh, the docs do say “click on the name of a snapshot to show it”. I guess the way it is said did not ring my bell. Sorry.
If you can think of better/clearer wording I’m happy to change it
No, now that I understand it, it is clear. 
Thank you.