we can't use an event filter on the top level webview, because it
ignores the return value of the filter and leads to Anki thinking
keys have been pressed twice
and if we use an event filter on the focusProxy(), the
keypress/release events are sent even when a text field is currently
focused, leading to shortcuts being triggered when typing in the answer
to solve this, we move away from handling the key press events
directly, and instead install shortcuts for the events we want to
trigger. in addition to the global shortcuts, each state can install
its own shortcuts, which we remove when transitioning to a new state
also remove the unused canFocus argument to ankiwebview, and accept a parent
argument as required by the code in forms/
34dcf64d76