Control and Alt are special in that they aren't expected to switch levels, and so don't need to change what characters are output.
Use in layouts by adding `modifier: Control` or `modifier: Alt` in place of `text: "foo"`.
The latching of the modifier will force the keyboard to emit raw key presses and prevent it from outputting text.
Erasing with zwp_text_input_v3 version 1 requires bytes, and bytes require get_surrounding_text. That, however, is optional. That's a mistake in protocol design.
Easiest to drop this until the mess is solved on the protocol side.
This fixes some rendering things which would happen with multiple state-sharing buttons. It also removes some interfaces exposing rows, views, layouts, and buttons, bringing the code closer to removing them from the FFI entirely.
