https://bugs.winehq.org/show_bug.cgi?id=50759
--- Comment #3 from Jacek Caban jacek@codeweavers.com --- It was intentional. If you don't have Gecko in shared location, Wine will install it on demand. If you want to force installing it, you may use: wine regsvr32 -i mshtml (as mentioned in the commit). Why do you want it installed on prefix creation?