TextField should not draw its background when disabled/not editable in 242+

[rock3r]

It looks like the platform changed how the background and borders are drawn in 242, and probably the value of TextField.disabledBackground too. Now, if the field is not enabled or editable, the background is simply not drawn.

We need to update our code accordingly, because we're drawing it and it looks wrong.

This seems to only be a problem in the bridge, because we use values in standalone that mask the issue, but a better solution is needed.

[rock3r]

Also need to check TextAreas, and see if we handle readonly correctly.