I was adding a new folder with the "Create Folder" popup menu and when I was naming it I noticed that Opus allows the use of slashes in the naming field. I don't know much about this but I do know that windows doesn't allow certain characters and I figure it would be nice if Opus displayed a similar notification to what Windows displays when you type in an offending character. In Opus, the forward slashes simply aren't in the name after you click "OK." The backslashes make the Create Folder text field stop as if you have written too many characters when you have not. I tested other characters and they just woulnd't appear in the text field, kind of like how Windows does, but without a notification.
Not a huge deal, just a little something I noticed.