Since the 5.4 upgrade, I was able to have dolphin and the folder-view applet opening folder on double click and selecting on single click. This is nice. However In System Settings, I now need to double click on an icon to open it, while selecting makes no sense, which I find too bad. It's the same on help, I have to double click on an item from the left list to update the main panel (where the help is displayed). I guess it's the same on other applications. I would rather define this behaviour only where the selection makes sense. Reproducible: Always
Somehow noone cares and me neither :P I'm now used to it.