Can't theme the background colour.

[WadeWT]

Thumb-Key Version
2.1.0

Describe the bug
The non keyboard area of the keyboard is always grey. I have tried changing all of the colours in Color.kt but the sides of the keyboard will always be grey. For proper theming support this colour should be able to be changed. I tried myself but don't really know what's causing it.

[dessalines]

Could you circle / highlight which area this is? I can't really tell.

[WadeWT]

These areas.

[dessalines]

We can't theme that unfortunately, its based on the application's background. If you have a launcher or some other app that uses transparency, you'll see that thumb-key only takes up as much space as it shows.

[WadeWT]

Ahh, I see. Perhaps an option for it to extend the full width of the device with some themeable element would be nice.

[WadeWT]

#464