--- a/dom/xul/nsXULElement.cpp
+++ b/dom/xul/nsXULElement.cpp
@@ -1106,34 +1106,21 @@ nsXULElement::AfterSetAttr(int32_t aName
                       aValue->Equals(NS_LITERAL_STRING("true"), eCaseMatters));
                 } else if (aName == nsGkAtoms::chromemargin) {
                     SetChromeMargins(aValue);
                 } else if (aName == nsGkAtoms::windowtype &&
                            document && document->GetRootElement() == this) {
                     MaybeUpdatePrivateLifetime();
                 }
             }
-            // title, (in)activetitlebarcolor and drawintitlebar are settable on
+            // title and drawintitlebar are settable on
             // any root node (windows, dialogs, etc)
             if (document && document->GetRootElement() == this) {
                 if (aName == nsGkAtoms::title) {
                     document->NotifyPossibleTitleChange(false);
-                } else if ((aName == nsGkAtoms::activetitlebarcolor ||
-                            aName == nsGkAtoms::inactivetitlebarcolor)) {
-                    nscolor color = NS_RGBA(0, 0, 0, 0);
-                    if (aValue->Type() == nsAttrValue::eColor) {
-                        aValue->GetColorValue(color);
-                    } else {
-                        nsAutoString tmp;
-                        nsAttrValue attrValue;
-                        aValue->ToString(tmp);
-                        attrValue.ParseColor(tmp);
-                        attrValue.GetColorValue(color);
-                    }
-                    SetTitlebarColor(color, aName == nsGkAtoms::activetitlebarcolor);
                 } else if (aName == nsGkAtoms::drawintitlebar) {
                     SetDrawsInTitlebar(
                         aValue->Equals(NS_LITERAL_STRING("true"), eCaseMatters));
                 } else if (aName == nsGkAtoms::drawtitle) {
                     SetDrawsTitle(
                         aValue->Equals(NS_LITERAL_STRING("true"), eCaseMatters));
                 } else if (aName == nsGkAtoms::localedir) {
                     // if the localedir changed on the root element, reset the document direction
@@ -1163,21 +1150,17 @@ nsXULElement::AfterSetAttr(int32_t aName
                     HideWindowChrome(false);
                 } else if (aName == nsGkAtoms::chromemargin) {
                     ResetChromeMargins();
                 }
             }
 
             nsIDocument* doc = GetUncomposedDoc();
             if (doc && doc->GetRootElement() == this) {
-                if ((aName == nsGkAtoms::activetitlebarcolor ||
-                     aName == nsGkAtoms::inactivetitlebarcolor)) {
-                    // Use 0, 0, 0, 0 as the "none" color.
-                    SetTitlebarColor(NS_RGBA(0, 0, 0, 0), aName == nsGkAtoms::activetitlebarcolor);
-                } else if (aName == nsGkAtoms::localedir) {
+                if (aName == nsGkAtoms::localedir) {
                     // if the localedir changed on the root element, reset the document direction
                     XULDocument* xuldoc = doc->AsXULDocument();
                     if (xuldoc) {
                         xuldoc->ResetDocumentDirection();
                     }
                 } else if ((aName == nsGkAtoms::lwtheme ||
                             aName == nsGkAtoms::lwthemetextcolor)) {
                     // if the lwtheme changed, make sure to restyle appropriately
@@ -1810,25 +1793,16 @@ nsXULElement::GetWindowWidget()
             nsCOMPtr<nsIWidget> mainWidget;
             baseWindow->GetMainWidget(getter_AddRefs(mainWidget));
             return mainWidget;
         }
     }
     return nullptr;
 }
 
-void
-nsXULElement::SetTitlebarColor(nscolor aColor, bool aActive)
-{
-    nsIWidget* mainWidget = GetWindowWidget();
-    if (mainWidget) {
-        mainWidget->SetWindowTitlebarColor(aColor, aActive);
-    }
-}
-
 class SetDrawInTitleBarEvent : public Runnable
 {
 public:
   SetDrawInTitleBarEvent(nsIWidget* aWidget, bool aState)
     : mozilla::Runnable("SetDrawInTitleBarEvent")
     , mWidget(aWidget)
     , mState(aState)
   {}

--- a/dom/xul/nsXULElement.h
+++ b/dom/xul/nsXULElement.h
@@ -732,17 +732,16 @@ protected:
     void MaybeAddPopupListener(nsAtom* aLocalName);
 
     nsIWidget* GetWindowWidget();
 
     // attribute setters for widget
     nsresult HideWindowChrome(bool aShouldHide);
     void SetChromeMargins(const nsAttrValue* aValue);
     void ResetChromeMargins();
-    void SetTitlebarColor(nscolor aColor, bool aActive);
 
     void SetDrawsInTitlebar(bool aState);
     void SetDrawsTitle(bool aState);
     void UpdateBrightTitlebarForeground(nsIDocument* aDocument);
 
     void RemoveBroadcaster(const nsAString & broadcasterId);
 
 protected:

--- a/xpcom/ds/nsGkAtomList.h
+++ b/xpcom/ds/nsGkAtomList.h
@@ -56,17 +56,16 @@ GK_ATOM(abort, "abort")
 GK_ATOM(above, "above")
 GK_ATOM(acceltext, "acceltext")
 GK_ATOM(accept, "accept")
 GK_ATOM(acceptcharset, "accept-charset")
 GK_ATOM(accesskey, "accesskey")
 GK_ATOM(acronym, "acronym")
 GK_ATOM(action, "action")
 GK_ATOM(active, "active")
-GK_ATOM(activetitlebarcolor, "activetitlebarcolor")
 GK_ATOM(activateontab, "activateontab")
 GK_ATOM(actuate, "actuate")
 GK_ATOM(address, "address")
 GK_ATOM(after, "after")
 GK_ATOM(after_end, "after_end")
 GK_ATOM(after_start, "after_start")
 GK_ATOM(align, "align")
 GK_ATOM(alink, "alink")
@@ -555,17 +554,16 @@ GK_ATOM(ignorekeys, "ignorekeys")
 GK_ATOM(ignoreuserfocus, "ignoreuserfocus")
 GK_ATOM(ilayer, "ilayer")
 GK_ATOM(image, "image")
 GK_ATOM(imageClickedPoint, "image-clicked-point")
 GK_ATOM(img, "img")
 GK_ATOM(implementation, "implementation")
 GK_ATOM(implements, "implements")
 GK_ATOM(import, "import")
-GK_ATOM(inactivetitlebarcolor, "inactivetitlebarcolor")
 GK_ATOM(include, "include")
 GK_ATOM(includes, "includes")
 GK_ATOM(increment, "increment")
 GK_ATOM(indent, "indent")
 GK_ATOM(indeterminate, "indeterminate")
 GK_ATOM(index, "index")
 GK_ATOM(infer, "infer")
 GK_ATOM(infinity, "infinity")