Create a new Button instance.
@memberof Button
@constructs
@param {Object} [props] - A dictionary of properties to initialize a Button instance with.
@static
function create(props) {
    var button = Object.create(this);

    _canvasWidget2.default.create.call(button);

    Object.assign(button, Button.defaults, props);

    if (props.value) button.__value = props.value;

    button.init();

    return button;
  }