Situation: I have a lot of images, I'd like to view them like in some standard image viewer (fullscreen, for example gpicview) and scroll with <- and -> (prev/next), but I'd like to make some kind of selection/decision on some images, so I can make afterwards some bulk operation on this selection.
For example, I shoot 100 photos on some occasion and want to select about 20-30 decent to keep and rest to delete, but it is very tedious to make such selection in file manager with thumbnails.
I found a question like mine is there a basic photo viewer that lets you flag individual photos for batch processing?, and it has one answer, which has big effort in. But still, is there a more simple solution nowadays? It seems so useful application, I can't believe there is no such available.
For your user case, i.e. selecting files for deletion, you can, while viewing the pictures full scree, directly hit Delete to move a file to the trash.
Otherwise, selecting files to do something with it later can easily be done in full fledged photo management application, such as Shotwell, which is installed by default on Ubuntu, or Digikam. You can "star" pictures with a shortcut key and as such easily select the best pictures. You also can "flag" pictures using a shortcut key. In your user case, you would flag all of your current pictures, then select the starred ones and remove the flag from these. You can then do something with the remaining flagged images.