Adding new key in Custom property and Keymap

[yoengbae]

Some devices have more keys of now it support(e.g. Clear with keycode -8)
Can you make an option for these additional keys?

[Feodor0090]

To play, usually you need only 2/4/6/8/5 keys. For working in applications you will have to use qwerty input mode anyway, because after "delete" button you will probably ask for "enter" and so on.

So, i'm against bloating "gaming" mappings further.

Btw, qwerty mode actually ignores delete key (at least on X11/gtk3, just checked) - that's the real issue here to fix.