--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -477,16 +477,18 @@ nsWindow::nsWindow()
     mTransparencyBitmapHeight = 0;
 
 #if GTK_CHECK_VERSION(3,4,0)
     mLastScrollEventTime = GDK_CURRENT_TIME;
 #endif
     mPendingConfigures = 0;
     mCSDSupportLevel = CSD_SUPPORT_NONE;
     mDrawInTitlebar = false;
+
+    mHasAlphaVisual = false;
 }
 
 nsWindow::~nsWindow()
 {
     LOG(("nsWindow::~nsWindow() [%p]\n", (void *)this));
 
     delete[] mTransparencyBitmap;
     mTransparencyBitmap = nullptr;
@@ -2129,17 +2131,17 @@ nsWindow::OnExposeEvent(cairo_t *cr)
 
     // Our bounds may have changed after calling WillPaintWindow.  Clip
     // to the new bounds here.  The region is relative to this
     // window.
     region.And(region, LayoutDeviceIntRect(0, 0, mBounds.width, mBounds.height));
 
     bool shaped = false;
     if (eTransparencyTransparent == GetTransparencyMode()) {
-        if (IsComposited()) {
+        if (mHasAlphaVisual) {
             // Remove possible shape mask from when window manger was not
             // previously compositing.
             static_cast<nsWindow*>(GetTopLevelWidget())->
                 ClearTransparencyBitmap();
         } else {
             shaped = true;
         }
     }
@@ -2232,17 +2234,17 @@ nsWindow::OnExposeEvent(cairo_t *cr)
 
 #endif // MOZ_X11
 
     bool painted = false;
     {
       if (GetLayerManager()->GetBackendType() == LayersBackend::LAYERS_BASIC) {
         if (GetTransparencyMode() == eTransparencyTransparent &&
             layerBuffering == BufferMode::BUFFER_NONE &&
-            IsComposited()) {
+            mHasAlphaVisual) {
           // If our draw target is unbuffered and we use an alpha channel,
           // clear the image beforehand to ensure we don't get artifacts from a
           // reused SHM image. See bug 1258086.
           dt->ClearRect(Rect(boundsRect));
         }
         AutoLayerManagerSetup setupLayerManager(this, ctx, layerBuffering);
         painted = listener->PaintWindow(this, region);
 
@@ -3656,18 +3658,18 @@ nsWindow::Create(nsIWidget* aParent,
     // figure out our parent window
     GtkWidget      *parentMozContainer = nullptr;
     GtkContainer   *parentGtkContainer = nullptr;
     GdkWindow      *parentGdkWindow = nullptr;
     GtkWindow      *topLevelParent = nullptr;
     nsWindow       *parentnsWindow = nullptr;
     GtkWidget      *eventWidget = nullptr;
     bool            drawToContainer = false;
-    bool            useAlphaVisual = (mWindowType == eWindowType_popup &&
-                                     aInitData->mSupportTranslucency);
+    bool            needsAlphaVisual = (mWindowType == eWindowType_popup &&
+                                       aInitData->mSupportTranslucency);
 
     if (aParent) {
         parentnsWindow = static_cast<nsWindow*>(aParent);
         parentGdkWindow = parentnsWindow->mGdkWindow;
     } else if (aNativeParent && GDK_IS_WINDOW(aNativeParent)) {
         parentGdkWindow = GDK_WINDOW(aNativeParent);
         parentnsWindow = get_window_for_gdk_window(parentGdkWindow);
         if (!parentnsWindow)
@@ -3726,32 +3728,38 @@ nsWindow::Create(nsIWidget* aParent,
         // before the widget is realized.
         if (mIsX11Display && useWebRender) {
             auto display =
                 GDK_DISPLAY_XDISPLAY(gtk_widget_get_display(mShell));
             auto screen = gtk_widget_get_screen(mShell);
             int screenNumber = GDK_SCREEN_XNUMBER(screen);
             int visualId = 0;
             if (GLContextGLX::FindVisual(display, screenNumber,
-                                         useWebRender, useAlphaVisual,
+                                         useWebRender, needsAlphaVisual,
                                          &visualId)) {
                 // If we're using CSD, rendering will go through mContainer, but
                 // it will inherit this visual as it is a child of mShell.
                 gtk_widget_set_visual(mShell,
                                       gdk_x11_screen_lookup_visual(screen,
                                                                    visualId));
+                mHasAlphaVisual = true;
+            } else {
+                NS_WARNING("We're missing X11 Visual for WebRender!");
             }
         } else
 #endif // MOZ_X11
         {
-            if (useAlphaVisual) {
+            if (needsAlphaVisual) {
                 GdkScreen *screen = gtk_widget_get_screen(mShell);
                 if (gdk_screen_is_composited(screen)) {
                     GdkVisual *visual = gdk_screen_get_rgba_visual(screen);
-                    gtk_widget_set_visual(mShell, visual);
+                    if (visual) {
+                        gtk_widget_set_visual(mShell, visual);
+                        mHasAlphaVisual = true;
+                    }
                 }
             }
         }
 
         // We only move a general managed toplevel window if someone has
         // actually placed the window somewhere.  If no placement has taken
         // place, we just let the window manager Do The Right Thing.
         NativeResize();
@@ -4125,17 +4133,17 @@ nsWindow::Create(nsIWidget* aParent,
 #ifdef MOZ_X11
     if (mIsX11Display && mGdkWindow) {
       mXDisplay = GDK_WINDOW_XDISPLAY(mGdkWindow);
       mXWindow = gdk_x11_window_get_xid(mGdkWindow);
 
       GdkVisual* gdkVisual = gdk_window_get_visual(mGdkWindow);
       mXVisual = gdk_x11_visual_get_xvisual(gdkVisual);
       mXDepth = gdk_visual_get_depth(gdkVisual);
-      bool shaped = useAlphaVisual && !IsComposited();
+      bool shaped = needsAlphaVisual && !mHasAlphaVisual;
 
       mSurfaceProvider.Initialize(mXDisplay, mXWindow, mXVisual, mXDepth,
                                   shaped);
     }
 #ifdef MOZ_WAYLAND
     else if (!mIsX11Display) {
       mSurfaceProvider.Initialize(this);
     }
@@ -7185,34 +7193,20 @@ nsWindow::RoundsWidgetCoordinatesTo()
     return GdkScaleFactor();
 }
 
 void nsWindow::GetCompositorWidgetInitData(mozilla::widget::CompositorWidgetInitData* aInitData)
 {
   *aInitData = mozilla::widget::GtkCompositorWidgetInitData(
                                 (mXWindow != X11None) ? mXWindow : (uintptr_t)nullptr,
                                 mXDisplay ? nsCString(XDisplayString(mXDisplay)) : nsCString(),
-                                mIsTransparent && !IsComposited(),
+                                mIsTransparent && !mHasAlphaVisual,
                                 GetClientSize());
 }
 
-bool
-nsWindow::IsComposited() const
-{
-  if (!mGdkWindow) {
-    NS_WARNING("nsWindow::HasARGBVisual called before realization!");
-    return false;
-  }
-
-  GdkScreen* gdkScreen = gdk_window_get_screen(mGdkWindow);
-  return gdk_screen_is_composited(gdkScreen) &&
-         (gdk_window_get_visual(mGdkWindow)
-            == gdk_screen_get_rgba_visual(gdkScreen));
-}
-
 #ifdef MOZ_WAYLAND
 wl_display*
 nsWindow::GetWaylandDisplay()
 {
   // Available as of GTK 3.8+
   static auto sGdkWaylandDisplayGetWlDisplay =
       (wl_display *(*)(GdkDisplay *))
       dlsym(RTLD_DEFAULT, "gdk_wayland_display_get_wl_display");

--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -486,17 +486,16 @@ private:
       CheckForRollup(0, 0, false, true);
     }
 
     bool               GetDragInfo(mozilla::WidgetMouseEvent* aMouseEvent,
                                    GdkWindow** aWindow, gint* aButton,
                                    gint* aRootX, gint* aRootY);
     void               ClearCachedResources();
     nsIWidgetListener* GetListener();
-    bool               IsComposited() const;
 
     void               UpdateClientOffsetForCSDWindow();
 
     nsWindow*          GetTransientForWindowIfPopup();
     bool               IsHandlingTouchSequence(GdkEventSequence* aSequence);
 
 #ifdef MOZ_X11
     typedef enum { GTK_WIDGET_COMPOSIDED_DEFAULT = 0,
@@ -604,16 +603,19 @@ private:
     static GdkCursor   *gsGtkCursorCache[eCursorCount];
 
     // Transparency
     bool         mIsTransparent;
     // This bitmap tracks which pixels are transparent. We don't support
     // full translucency at this time; each pixel is either fully opaque
     // or fully transparent.
     gchar*       mTransparencyBitmap;
+    // True when we're on compositing window manager and this
+    // window is using visual with alpha channel.
+    bool         mHasAlphaVisual;
 
     // all of our DND stuff
     void   InitDragEvent(mozilla::WidgetDragEvent& aEvent);
 
     float              mLastMotionPressure;
 
     // Remember the last sizemode so that we can restore it when
     // leaving fullscreen