acrobatusers.com sample - 2016/04/13 #2

// Custom Keystroke script for dropdown
if (!event.willCommit) {

    var layers = this.getOCGs();

    for (var i = 0; i < layers.length; i++) {
        if (layers[i].name == event.changeEx) {
            layers[i].state = true;  // Turn on layer
        }
    }
}