Change 110610 had a related patch set uploaded by 01tonythomas:
Ticking search in all namespaces should tick all the remaining checkboxes.

https://gerrit.wikimedia.org/r/110610

https://www.mediawiki.org/wiki/Special:Preferences#mw-prefsection-searchoptions is... bad.

The real answer here is to fix the overall design problem. But for now, Gerrit change 110610 may be a small step forward. I'm still trying to imagine what my reaction would be to the proposed behavior. Perhaps we should do better to mimic [[mw:Special:Search]]? I don't know.

Change 110610 merged by jenkins-bot:
Ticking 'Search in all namespaces' in prefs should disable other checkboxes

https://gerrit.wikimedia.org/r/110610