You make a good argument though, about consistency between fullscreen and desktop applications. Maybe the Pandora key should never be used by an application, it should always be handled by the desktop in a consistent way, just like the Windows/super key on a desktop: a key that the application can't even bind against, one that always always gets handled by the OS. That way, no matter what happens to the program, you can be guaranteed that hitting the Pandora button (combinations) will do something, so long as the desktop is still functioning.
I disagree, this consistency is only really noticeable for the OS developer. For the end user the Pandora key will be used to exit an application - gracefully (through an in-game menu) or forced (hold for X seconds).
The obvious drawback is that as long as it's not integrated in most apps the proposed behaviour is not consistent.
Currently the kill-overlay does not work for fullscreen apps so it's kinda useless, just like the Windows key when you are in a game (well it will bring you back to the desktop in most cases, but it's hit more accidentally than intentional and seldom used in its purpose).
Though thinking about it the past days I have come to the conclusion that the Fn+Q combo to exit (gracefully, yet immediate or with a single prompt) and the Start button to open up a menu (which probably should provide an exit option at any point) should be enough to cover this part.
The Select or Pandora button would just be provided as an alternative to Fn+Q as that combo is immediately visible.
Do we actually need to have a dedicated exit button aside from Fn+Q at all? If start is already the default key to open a game menu and space the default to open the emulator menu, then it is quite reasonable to assume that those menus will contain a quit option.
Yes I have to come the conclusion that this should suffice as long as the standard encourages to provide a menu (brought up by pressing Start) with a quit option and the Fn+Q combo at any point. The former is probably obvious to any new user, while the latter might need to be discovered first, but then will be rather obvious, too.
The Pandora button then stays in functionality as it currently is, but I propose the kill menu (which is activated by holding the button for a few seconds) is re-designed to work like an overlay menu from current console generations (think pressing the big X button on an X-Box controller, the home button on the Wii or the PS button on a PS3).
Pushing and holding the button for a few seconds should then bring up a menu (which is ensured to pop-up in front of the current running application), pause any running application (which might not be possible(?)) and show options to kill the currently active application, return to the desktop, turn off the Pandora, or open a terminal in the foreground.
