Issue 1606 - Don't create overlays for hidden elements

include.postload.js

Index: include.postload.js
===================================================================
--- a/include.postload.js
+++ b/include.postload.js
@@ -190,6 +190,19 @@
   return [l, t];
 }
 
+function isDisplayed(element)
+{
+  while (element)
+  {
+    if (getComputedStyle(element).display == "none")
+      return false;
+
+    element = element.parentElement;
+  }
+
+  return true;
+}
+
 // Adds an overlay to an element, which is probably a Flash object
 function addElementOverlay(elt) {
   // If this element is enclosed in an object tag, we prefer to block that instead
@@ -200,6 +213,12 @@
   // because we don't know how to construct a filter rule for it
   if(!hasFilters(elt))
     return;
+
+  // If the element isn't rendered (since its or one of its ancestor's
+  // "diplay" property is "none"), the overlay wouldn't match the element.
+  if (!isDisplayed(elt))
+    return;
+
   var thisStyle = getComputedStyle(elt, null);
   var overlay = document.createElement('div');
   overlay.prisoner = elt;