Sorry, I have to report that there seems to be a bug affecting only Firefox which causes problems with things like universal camera navigation. In Firefox, whenever I use directional keys to try to control a universal camera I find that only the forward and back keys work. The left/right buttons tend to cause the browser to shift focus to something other than the canvas.
In my app, instead of strafing the universal camera, pressing left or right would cause an input field to receive focus. On other pages it seems that other items on the page can receive focus when pressing left or right, for instance in this playground; Babylon.js Playground pressing left or right causes a panel to receive focus.
I don’t get this issue on chromium based browsers. Babylon seem better able to keep the focus on the WebGL canvas in chromium. I don’t have a mac to test this on Safari.
I know Firefox is not the most popular browser these days but I still thought I should flag this up.