Yes, you are correct. It seems the function was commented out a long time ago and forgotten about. I've just restored it. When you hide the menu bar it will come back next time you run the game.
The proper way is to set things up so that the bar is hidden for arcade games, but shows for computers/consoles. To make that happen, create a file called arcade.ini in the ini folder, and put one line into it: menu 0
For individual games and systems, you can right-click on the game, Properties, Miscellaneous, and adjust the checkbox "Show Menu".