message: Fix typo in view cover
diff: show()
  {
  this.viewer.addClass("opened");
  - $("html,body").addClass("image-viewer.opened");
  + $("html,body").addClass("image-viewer-opened");
  }
  hide()
  {
  this.viewer.removeClass("opened");
  - $("html,body").removeClass("image-viewer.opened");
  + $("html,body").removeClass("image-viewer-opened");
  }
  }
  