I was testing this for a user in #kde. When I attempted to revert the choice, I got the Kdialog: Current configuration for the input method: * Active configuration: missing (normally missing) * Automatic configuration: none (normally ibus or fcitx or uim) * Number of valid choices: 1 (normally 1) The configuration set by im-config is activated by re-starting X. Explicit selection is not required to enable the automatic configuration if the active one is default/auto/cjkv/missing. To fix, the file .kde/share/config/plasma-desktop-appletsrc must be edited. If one change line that starts: RightButton;NoModifier= to: RightButton;NoModifier=contextmenu then save. Logout and back in, the default is restored. Reproducible: Always Steps to Reproduce: 1. Right-click on the desktop, choose Desktop Settings then ▶ Mouse actions then ▶ Right-Button and select Application Launcher 2. Right-click on the desktop again, and attempt to change desktop settings again. 3. Kdialog as above Actual Results: Desktop settings are changed, and can't be changed back to the default in the gui/context menu. Expected Results: When attempting to change back, the context menu should allow that.
Same thing here: Right click the desktop > Default Desktop Settings > Mouse Actions > Right-Button > Select: Application Launcher, hit Apply. Then there is no way to change back, except for altering file: .kde/share/config/plasma-desktop-appletsrc then logging out and back in. GUI should allowing changing back to settings again. Definately a bug. Also I think System-Settings menu should allow this.
This no longer happens in Plasma 5.5.3, so closing as fixed.