I would submit a Feedback request, but I can’t (my license expired yesterday)
It seems that in 2016r4.1 (at least under OSX) that if you set the IDE search to “Match Case”, do some searches, and then uncheck “MatchCase”
it STILL matches case, until you RESTART Xojo
I told it to search for "user (yes with a preceding quote, and lower case) AFTER unchecking Matchcase.
it actually didn’t even find all the lowercase versions, restarted Xojo and it found them all (a few hundred in both Upper and lowercase)