--- a/embedding/browser/nsDocShellTreeOwner.cpp
+++ b/embedding/browser/nsDocShellTreeOwner.cpp
@@ -1180,16 +1180,20 @@ nsDefaultTooltipTextProvider::GetNodeTex
                 uint32_t count = std::min(listLength, TRUNCATED_FILE_COUNT);
                 for (uint32_t i = 1; i < count; ++i) {
                   nsString fileName;
                   fl->UnsafeItem(i).GetAsFile()->GetName(fileName);
                   outText.Append(NS_LITERAL_STRING("\n"));
                   outText.Append(fileName);
                 }
               }
+            } else if (content->IsXULElement() &&
+                       NS_SUCCEEDED(currElement->GetAttribute(NS_LITERAL_STRING("tooltiptext"), outText)) &&
+                       outText.Length()) {
+              found = true;
             } else if (NS_SUCCEEDED(currElement->GetAttribute(NS_LITERAL_STRING("title"), outText)) &&
                        outText.Length()) {
               found = true;
             }
           }
           if (!found) {
             // ...ok, that didn't work, try it in the XLink namespace
             NS_NAMED_LITERAL_STRING(xlinkNS, "http://www.w3.org/1999/xlink");