MSFX - IE5 theme for Firefox

/* LoadingBar.uc.js */
// Location Bar Enhancer5.1; Loading Bar0.3.0
// Firefox 87+

(function(){
    var cssStr = `
            #browser-bottombox {
background-image: linear-gradient(90deg, rgba(0,0,128,0), rgba(0,0,128,0) 5px, rgba(0,0,128,1) 5px, rgba(0,0,128,1) 2px), linear-gradient(to right, rgba(0,0,128) 0%, rgba(0,0,128) 5%, rgba(0,0,128) 10%, rgba(0,0,128) 20%,rgba(0,0,128) 30%, rgba(0,0,128) 40%, rgba(0,0,128) 50%, rgba(0,0,128) 60%, rgba(0,0,128,5) 70%, rgba(0,0,128,6) 80%,rgba(0,0,128,.7) 100%);
                background-size:0 0;
                margin-right: 200px !important;
                margin-left: 1600px !important;
                background-position: left center !important;
                background-repeat: no-repeat;
                transition: background-size 1350ms ease 0s;
                
            }
            #browser-bottombox:not([style="background-size: 0% 100%;"]) {
                animation:  progress-bar-stripes 2s linear infinite;
            }
            @keyframes progress-bar-stripes {
                
                from {
                    background-position: 0 0;
                }
                to {
                    background-position: 0 0;
                }
            }
    `.replace(/\s{2,}|\r|\n/,"");
    
    var style = document.createProcessingInstruction("xml-stylesheet", "type=\"text/css\"" + " href=\"data:text/css;base64," + btoa(cssStr) + "\"");
    var mainW = document.getElementById("main-window");
    document.insertBefore(style, mainW);

    function main(window) {
      var {document, gBrowser} = window;
      function $(id) { return document.getElementById(id) };
      var urlbar = $("browser-bottombox");
      let pageProgress = 0;
      let async = makeWindowHelpers(window).async;
      var LoadingBar = {
        listener: {
          onChangeTab: function(e) {
            urlbar.style.backgroundSize = '0% 100%';
            pageProgress = 0;
          },
          onProgressChange: function(aBrowser,webProgress,request,curSelfProgress,maxSelfProgress,curTotalProgress,maxTotalProgress) {
            if (gBrowser.contentDocument === aBrowser.contentDocument) {
                var val = (curTotalProgress-1)/(maxTotalProgress-1);
                pageProgress = val;
                urlbar.style.backgroundSize = (100*val) + '% 100%';
                if (val > 0.9)
                  async(function() {
                    if (pageProgress > 0.95)
                        urlbar.style.backgroundSize = '1% 100%';
                }, 1000);
            }
          },
          onStateChange: function() {
            if (pageProgress > 0.95){
                async(function() {
                    urlbar.style.backgroundSize = '0% 100%';
                    pageProgress = 0;
                }, 1000);
            }else{
                urlbar.style.backgroundSize = '0% 100%';
            }
          }
        }
      };

      gBrowser.tabContainer.addEventListener('TabSelect',LoadingBar.listener.onChangeTab,false);
      gBrowser.addTabsProgressListener(LoadingBar.listener);

      unload(function() {
        gBrowser.tabContainer.removeEventListener('TabSelect',LoadingBar.listener.onChangeTab,false);

        gBrowser.removeTabsProgressListener(LoadingBar.listener);
      }, window);
    }



    watchWindows(main, "navigator:browser");

    function runOnLoad(window, callback, winType) {
      window.addEventListener("load", function() {
        window.removeEventListener("load", arguments.callee, false);

        if (window.document.documentElement.getAttribute("windowtype") == winType)
          callback(window);
      }, false);
    }

    function runOnWindows(callback, winType) {
      function watcher(window) {
        try {
          callback(window);
        }
        catch(ex) {}
      }

      let browserWindows = Services.wm.getEnumerator(winType);
      while (browserWindows.hasMoreElements()) {
        let browserWindow = browserWindows.getNext();
        if (browserWindow.document.readyState == "complete")
          watcher(browserWindow);
        else
          runOnLoad(browserWindow, watcher, winType);
      }
    }

    function watchWindows(callback, winType) {
      function watcher(window) {
        try {
          callback(window);
        }
        catch(ex) {}
      }

      runOnWindows(callback, winType);

      function windowWatcher(subject, topic) {
        if (topic == "domwindowopened")
          runOnLoad(subject, watcher, winType);
      }
      Services.ww.registerNotification(windowWatcher);

      unload(function() { Services.ww.unregisterNotification(windowWatcher) });
    }

    function unload(callback, container) {
      let unloaders = unload.unloaders;
      if (unloaders == null)
        unloaders = unload.unloaders = [];

      if (callback == null) {
        unloaders.slice().forEach(function(unloader) { unloader() });
        unloaders.length = 0;
        return null;
      }

      if (container != null) {
        container.addEventListener("unload", removeUnloader, false);

        let origCallback = callback;
        callback = function() {
          container.removeEventListener("unload", removeUnloader, false);
          origCallback();
        }
      }

      function unloader() {
        try {
          callback();
        }
        catch(ex) {}
      }
      unloaders.push(unloader);


    function removeUnloader() {
        let index = unloaders.indexOf(unloader);
        if (index != -1)
          unloaders.splice(index, 1);
      }
      return removeUnloader;
    }
    
    function makeWindowHelpers(window) {
      let {clearTimeout, setTimeout} = window;

      function async(callback, delay) {
        delay = delay || 0;
        let timer = setTimeout(function() {
          stopTimer();
          callback();
        }, delay);

        function stopTimer() {
          if (timer == null)
            return;
          clearTimeout(timer);
          timer = null;
        }
      }

      return {
        async: async,
      };
    }

})();