The Held state is for modifier that should be off when the corresponding
key is released. If the user presses the modifier key and a normal key,
it would be in this state. The modifier would continue to be active when
the user moves to a different key part (a cancel, e.g. from Fn to Alt)
afterwards. To fix this, add the HeldPressed and HeldLockedPressed
states that reset to the Released state when cancelled.
Keeping the keys pressed can confuse some compositors, and the key codes
may change. Release any keys that are pressed while the keymap is
changing, and press them again afterwards.
