Sets popup default dimensions.
function mounted () {
    if (!inBrowser) {
      return;
    }

    /**
     * Center the popup on dual screens
     * http://stackoverflow.com/questions/4068373/center-a-popup-window-on-screen/32261263
     */
    var dualScreenLeft = $window.screenLeft !== undefined ? $window.screenLeft : screen.left;
    var dualScreenTop = $window.screenTop !== undefined ? $window.screenTop : screen.top;

    var width = $window.innerWidth ? $window.innerWidth : (document.documentElement.clientWidth ? document.documentElement.clientWidth : screen.width);
    var height = $window.innerHeight ? $window.innerHeight : (document.documentElement.clientHeight ? document.documentElement.clientHeight : screen.height);

    this.popup.left = ((width / 2) - (this.popup.width / 2)) + dualScreenLeft;
    this.popup.top = ((height / 2) - (this.popup.height / 2)) + dualScreenTop;
  }