I would like to see a more advanced filter panel or another panel for filtering keywords.
If keywords cats and dogs are selected, for instance, any photos with cats OR dogs are shown. If I want only photos with cats AND dogs shown the panel is useless. I know about the more advanced search (CTRL + F) and smart collections, but they are not as quick and intuitive to use as clicking the actual keywords used in a folder or collection.
A simple option to use AND (all) instead of OR (any) would be a huge improvement. I’ve seen many users wanting the same.
Even better, you could make a filter panel (at least for keywords) that is more like the keyword panel, in which keywords can be arranged in hierarchies. One for cats and another for dogs, for instance. Kinds of cats and dogs as sub keywords. If I choose one kind of cat and one kind of dog only photos of them together could be shown. You could even use the same way to change the checkbox content between check, minus and nothing for showing photos with keywords according to operators AND, OR or NOT instead. For instance, <and Cats> <and dogs> <or birds> <not fish> would show photos with cats and dogs together + any photos with birds - any photos with fish.
If you are afraid of messing with the simplicity for the most basic users you could at least make an extension with such functions. Or a non-default optional panel. Would’ve been greatly appreciated.