From KDE UserBase Wiki

    Dolphin usability notes

    2015: Select / Deselect vs. starting an item/file

    1. Open a folder in dolphin
    2. Switch to Compact Mode
    3. Try to explain to a novice person the difference between clicking on the icon rather than clicking on the item's text. (Icon click toggles item selection, Text click runs the item)

    Possible solution: look how it is been done since Windows 8 Windows Explorer:

    • Hovering the mouse shows an empty box if the file is not selected.
    • If the users clicks the empty box the file becomes selected and there is a check mark in the box.
    • When a file is already selected the checkmark is always visible.