On my wiki, I set $wgEnableMWSuggest to true (in a $wgConf setup), but then, when I have to search, the search does not go unless I press Enter twice instead of just once. This apparently does not apply to IE 9, but it's a problem in Firefox 8 and Chrome.
Version: unspecified
Severity: enhancement
OK, with $wgVectorUseSimpleSearch=true and $wgEnableMWSuggest=true, there's no problem.
So the new Vector modules don't have this bug, but the old mediawiki.legacy.mwsuggest module does.
I've rephrased the summary to reflect it and generalized it for all operating systems (not just Windows 7), I reproduced it on the latest trunk just now in Chrome on Mac OS X.
Since the legacy modules are no longer in active development, this will probably be left as-is until they are fully deprecated and removed.