Issue 154 - Added devtools panel showing blocked and blockable items

include.preload.js

Index: include.preload.js
===================================================================
--- a/include.preload.js
+++ b/include.preload.js
@@ -152,6 +152,53 @@
   observer.observe(style.parentNode, {childList: true});
 }
 
+function traceHiddenElements(document, selectors)
+{
+  function check(element)
+  {
+    var matchedSelectors = [];
+
+    for (var i = 0; i < selectors.length; i++)
+    {
+      var selector = selectors[i];
+      var elements = document.querySelectorAll(selector);
+
+      for (var j = 0; j < elements.length; j++)
+      {
+        if (getComputedStyle(elements[j]).display == "none")
+        {
+          matchedSelectors.push(selector);
+          break;
+        }
+      }
+    }
+
+    if (matchedSelectors.length > 0)
+      ext.backgroundPage.sendMessage({type: "trace-elemhide", selectors: matchedSelectors});
+  }
+
+  function trace()
+  {
+    check();
+
+    var MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
+    if (MutationObserver)
+    {
+      new MutationObserver(check).observe(document,
+      {
+        childList: true,
+        attributes: true,
+        subtree: true
+      });
+    }
+  }
+
+  if (document.readyState == "loading")
+    document.addEventListener("DOMContentLoaded", trace);
+  else
+    trace();
+}
+
 function init(document)
 {
   // use Shadow DOM if available to don't mess with web pages that
@@ -166,11 +213,12 @@
   }
 
   // Sets the currently used CSS rules for elemhide filters
-  var setElemhideCSSRules = function(selectors)
+  var setElemhideCSSRules = function(response)
   {
-    if (selectors.length == 0)
+    if (response.selectors.length == 0)
       return;
 
+    var selectors = response.selectors.slice(0);
     var style = document.createElement("style");
     style.setAttribute("type", "text/css");
 
@@ -206,6 +254,9 @@
         var selector = selectors.splice(0, SELECTOR_GROUP_SIZE).join(", ");
         style.sheet.insertRule(selector + " { display: none !important; }", i);
       }
+
+      if (response.trace)
+        traceHiddenElements(document, response.selectors);
     };
 
     setRules();