SUMMARY It is not possible to deactivate installing recommended dependencies (this is problematic because many unnecessary dependencies will be installed) or to enable installing suggested dependencies. STEPS TO REPRODUCE 1. Go to Settings -> Configure Muon Package Manager 2. Uncheck "Treat recommended packages as dependencies" or check "Treat suggested packages as dependencies" (so far so good) 3. Click Apply and Ok 4. Reopen the settings OBSERVED RESULT The changes have not been accepted/saved EXPECTED RESULT The changes should be applied and remembered correctly. SOFTWARE/OS VERSIONS Operating System: KDE neon 5.21 KDE Plasma Version: 5.21.4 KDE Frameworks Version: 5.81.0 Qt Version: 5.15.2 Kernel Version: 5.4.0-72-generic OS Type: 64-bit Graphics Platform: Wayland Processors: 4 × Intel® Core™ i5-3570K CPU @ 3.40GHz Memory: 7.2 GiB of RAM Graphics Processor: Mesa DRI Intel® HD Graphics 4000 ADDITIONAL INFORMATION In general it would be good if any optional dependencies could be selected by the user individually in the dialog shown when clicking on "Apply Changes", as virtually all other package managers do. The user may want some recommended/suggested dependencies, others not, so this should be more of a per-package descision rather than a global setting.
Of course it is good to have a global option on whether to select optional dependencies by default, but I think a per-package option/checkbox would be an important complement.
Closing as I'm not using muon anymore.