So this has happened before but I'm totally forgetting how I dealt with it, I may have reinstalled the mac client. But basically I try to open royals. and I get an error saying something about plist being read-only. I restart my computer, and when I log into my mac, I get the white screen error (somewhat common error on MacBooks, rebooting in safe mode, then restarting fixes this). So I boot in safe mode, everything seems fine, restart my computer to get back to normal boot. Now when I click maple, same as last time this happened, the game starts in a somewhat warped fullscreen mode that I cannot tab out of or minimize. Everything runs fine though. If I go in system settings in game and try to change to windowed mode, and i click "okay", I get that mac-sound "DONK" and it stays in full screen. Go back to settings, and see that windowed mode was not accepted. What on earth is going on? I think reinstalling the client fixed this but it was kind of an annoying this to have to go through.
Sounds like the wineskin screen settings were altered? Try clicking on the app while holding down Alt, and then should see an option for the screen options.