list should have a shortcut to select only one item and to reverse selection. It is common to use ^LMB. STEPS TO REPRODUCE 1. Right click on a window titlebar. 2. Go to "Show in Activities". 3. Ctrl + Left click on one of the activities. OBSERVED RESULT As for plain LMB click. EXPECTED RESULT Only clicked activity is selected if was not, every activity is selected if clicked one was selected before. GNU Linux/KDE Plasma: KDE Plasma Version: 5.21.4 KDE Frameworks Version: 5.81.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION BUG434621 is for related UX issue.
I meant "every activity is selected except the clicked one" in EXPECTED section, as it seems common intuitive behavior.
I'd like to add that as the "Show in Activities" menu is a checkbox list, it would be good if it could remain until dismissed. It's frustrating when trying to add a window to several (but not all) activities and have the menu disappear after each selection.