function findOverridden(event) {
  let modifiers = gModifiers.fromEvent(event);

  return Object.keys(gOverlays).map(id => gHotKeys[id]).some(hotkey => {
    return modifiers == hotkey.modifiers &&
           event.key.toLowerCase() == hotkey.key.toLowerCase();
  });
}
function findOverlay(event) {
  let evmodifiers = gModifiers.fromEvent(event);

  return Object.keys(gOverlays).find(id => {
    let {disabled, key, modifiers} = gOverlays[id];
    return !disabled &&
           evmodifiers == modifiers &&
           event.key.toLowerCase() == key.toLowerCase();
  });
}