private static boolean isActionOnlyKey(SignalEvent signal) {
// When modifier key is pressed on Mac it is instantly applied to modifiers.
// So we check on Mac that only "CMD" is pressed.
// On non-Mac when "CTRL" is the first key in sequence, there are no
// modifiers applied yet.
KeyModifier modifier = UserAgent.isMac() ? KeyModifier.META : KeyModifier.NONE;
return modifier.check(signal) && (signal.getKeyCode() == getActionKeyCode());
}