In mx 8.5 i saw a new feature Distraction View Mode Shift+F11 (great, thx ) but now F11 let your window become full screen i.s.o. your modeler ( windows taskbar become hidden ).
Forgotten User 18KmgnZfjD
Sounds more someting for the Indea Forum.
After a short search in the release notes i've found this: Mendix changed the F11 feature and add an extra Shift+F11 feature. See chapter 13 and 14 of https://docs.mendix.com/refguide/view-menu#full-screen