Last modified: 2014-02-17 05:05:13 UTC
Why not add some javascript for "Select all | Deselect all | Invert selection" on the namespace selectors?
If done, remove the note "Try prefixing your query with all: to search all content" on MediaWiki:Nonefound.
"All" and "None" were added to the "Advanced" tab, so only "Reverse" is left. "Other special pages" is way too generic to be useful, removing from this bug.
I don't think we should put an inverse button here. If anything, we need to be making this tab less cluttered.