hi, I tried to find the answer in the 3.8 manual, but did not success. How can i click on a folder in the collection listbox and have displayed the images only in that folder (not in the sub-folder) ? I dont want to shift-click for each folder.
I don’t believe there’s another way other than shift click.
How about filtering by film roll?
I am not too sure to understand fully the concept of Film Roll, but for me personnally, it has no value. Once images are imported and placed in folders, I do everything based on folder content (including obviously visualization).
So, SHFT-click is affecting only the folder where you apply it, right (according to what I tested) ? If I have made no mistake, it means that if I have 100 folders , I will have to SHFT-click 100 times… Would it be possible to have a config to set that for all folders ?
A ‘film roll’ (I hate that name) is a directory. 
https://docs.darktable.org/usermanual/3.8/en/module-reference/utility-modules/shared/collections/#files
The name of the film roll to which the image belongs (which is the same as the name of the folder in which the image resides).
If you open the ‘hamburger’ menu → preferences of the collections module, you’ll be able to set the property number of levels to show in lists (limited to 5). Then you can see that the film roll is just a directory:
I think it is important to mention that the film roll represents only the imported images of a directory. It does not directly reflect the file system, and changes in the file system are not visible before they are imported as well.
It may sound like a minor difference, but I think it is crucial for understanding the concept of darktable as DAM.
Yes, sure, but that’s true of all filters of the collections module. There’s nothing special about film roll in that respect; the folder filter works the same way.