"Using button 16 on a standard gamepad" is one of the designed way to display the fullscreen warning box. Since the Gamepad API doesn't dispatch normal events by default, we would need to add some custom event in GamepadService::NewButtonEvent() to enable doing this. Also since I don't have a gamepad, it would not be easy to test myself.

I have one question about this. When the user sees the notification box, how can they actually exit fullscreen? If they still need mouse or keyboard to do so, what's the point to support displaying this box via gamepad button? I don't have any experience with gamepad, but I guess when people exit fullscreen, it is likely that they have finished this game and are going to back use mouse/keyboard, so it is probably not a big issue to require an extra mouse/keyboard operation, though. Probably the point is just to display the information?

This is my fault. I did not write this carefully. The gamepad button should just exit full screen, not display the message. Button 16 is similar to Esc in the context of the game (like the PS button on a PS3 controller). Martin can you chime in here?

I'm not sure I know the best thing to do here off the top of my head. I see where you are going but worry about side effects of hard coding this in this way. I would say that we should not do this until we are sure we understand the ramifications. I'm sending this but to Andre and Luke to chime in.

Can I get more context on what button #16 is? I'm trying to map to a PS4/Xbox controller in my mind. From the perspective of a console gamer, the Guide button (PSN button) pops up social UI — friends, messaging, presence, way to respond to game invites, etc. And we are working on a game strategy to potentially include a version of that guide functionality within Firefox. So I would hate to do anything that precludes that. A more obvious option would be the "back" button on modern controllers — generally the button to the left of the "start" button. I put those in quotes as the latest generation of consoles have added new sharing functionality to those, but in the context of playing on a PC, I don't think it's unreasonable to use.

(In reply to avrignaud from comment #4) > Can I get more context on what button #16 is? I'm trying to map to a > PS4/Xbox controller in my mind. You can see https://w3c.github.io/gamepad/#remapping for the button mapping on Gamepad API.

Can we set up a brief chat? I'm not sure I fully understand what we're trying to do here, and there are possible ramifications with the new games UI we are thinking about for the browser in near future. Probably quickest to talk. Also, adding +luke@mozilla.com to bug.