Okay, so is that a bug or the intended behavior?
No bug, just not supported atm.
asyn
There are currently only three browsers supported, IE, Mozilla (not firefox) and Netscape (so effectively only one). This goes back years when the Script Shield was introduced.
No doubt they will be considering adding other browsers, I would imagine any priority would be based on the browser user base (firefox, chrome, etc.) and no firm plan or dates have been given.