sclass HFullScreenDim {
  S id = "dimThePage";
  int zIndex = 999;
  S color = "black";
  double opacity = 0.5;
  S onUndim;
  
  S html() {
    ret hcss("#" + id + replaceDollarVars([[ {
       position:fixed;
      top:0;
      bottom:0;
      left:0;
      right:0;
      background: $color;
      opacity: $opacity;
      z-index: $zIndex;
      /*pointer-events: none;*/
      visibility: hidden;
    }]], +color, +opacity, +zIndex))
      + div("", +id, onclick := nemptyLinesLL(js_undim(), onUndim));
  }
  
  S js_dim() {
    ret js_dollarVars([[document.getElementById($id).style.visibility = "visible";]], +id);
  }
  
  S js_undim() {
    ret js_dollarVars([[document.getElementById($id).style.visibility = "hidden";]], +id);
  }
}

Began life as a copy of #1032360