--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -3742,17 +3742,17 @@ nsWindow::Create(nsIWidget* aParent,
          *    are drawn by Gtk+ to mShell. Content is rendered to mContainer
          *    and we listen to the Gtk+ events on mContainer.
          * 3) We're running on Wayland. All gecko content is rendered
          *    to mContainer and we listen to the Gtk+ events on mContainer.
          */
         GtkStyleContext* style = gtk_widget_get_style_context(mShell);
         drawToContainer =
             !mIsX11Display ||
-            (mIsCSDAvailable && GetCSDSupportLevel() == CSD_SUPPORT_FLAT ) ||
+            (mIsCSDAvailable && GetCSDSupportLevel() == CSD_SUPPORT_CLIENT) ||
             gtk_style_context_has_class(style, "csd");
         eventWidget = (drawToContainer) ? container : mShell;
 
         gtk_widget_add_events(eventWidget, kEvents);
         if (drawToContainer)
             gtk_widget_add_events(mShell, GDK_PROPERTY_CHANGE_MASK);
 
         // Prevent GtkWindow from painting a background to avoid flickering.
@@ -6535,17 +6535,17 @@ nsWindow::SetNonClientMargins(LayoutDevi
 
 void
 nsWindow::SetDrawsInTitlebar(bool aState)
 {
   if (!mIsCSDAvailable || aState == mIsCSDEnabled)
       return;
 
   if (mShell) {
-      if (GetCSDSupportLevel() == CSD_SUPPORT_FULL) {
+      if (GetCSDSupportLevel() == CSD_SUPPORT_SYSTEM) {
           SetWindowDecoration(aState ? eBorderStyle_border : mBorderStyle);
       }
       else {
           /* Window manager does not support GDK_DECOR_BORDER,
            * emulate it by CSD.
            *
            * gtk_window_set_titlebar() works on unrealized widgets only,
            * we need to handle mShell carefully here.
@@ -6882,81 +6882,81 @@ nsWindow::GetCSDSupportLevel() {
     if (sCSDSupportLevel != CSD_SUPPORT_UNKNOWN) {
         return sCSDSupportLevel;
     }
 
     const char* currentDesktop = getenv("XDG_CURRENT_DESKTOP");
     if (currentDesktop) {
         // GNOME Flashback (fallback)
         if (strstr(currentDesktop, "GNOME-Flashback:GNOME") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         // gnome-shell
         } else if (strstr(currentDesktop, "GNOME") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FULL;
+            sCSDSupportLevel = CSD_SUPPORT_SYSTEM;
         } else if (strstr(currentDesktop, "XFCE") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         } else if (strstr(currentDesktop, "X-Cinnamon") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FULL;
+            sCSDSupportLevel = CSD_SUPPORT_SYSTEM;
         // KDE Plasma
         } else if (strstr(currentDesktop, "KDE") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         } else if (strstr(currentDesktop, "LXDE") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         } else if (strstr(currentDesktop, "openbox") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         } else if (strstr(currentDesktop, "i3") != nullptr) {
             sCSDSupportLevel = CSD_SUPPORT_NONE;
         } else if (strstr(currentDesktop, "MATE") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         // Ubuntu Unity
         } else if (strstr(currentDesktop, "Unity") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         // Elementary OS
         } else if (strstr(currentDesktop, "Pantheon") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FULL;
+            sCSDSupportLevel = CSD_SUPPORT_SYSTEM;
         } else if (strstr(currentDesktop, "LXQt") != nullptr) {
-            sCSDSupportLevel = CSD_SUPPORT_FULL;
+            sCSDSupportLevel = CSD_SUPPORT_SYSTEM;
         } else {
 // Release or beta builds are not supposed to be broken
 // so disable titlebar rendering on untested/unknown systems.
 #if defined(RELEASE_OR_BETA)
             sCSDSupportLevel = CSD_SUPPORT_NONE;
 #else
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
 #endif
         }
     } else {
         sCSDSupportLevel = CSD_SUPPORT_NONE;
     }
 
-    // We don't support CSD_SUPPORT_FULL on Wayland
+    // We don't support CSD_SUPPORT_SYSTEM on Wayland
     if (!GDK_IS_X11_DISPLAY(gdk_display_get_default()) &&
-        sCSDSupportLevel == CSD_SUPPORT_FULL) {
-        sCSDSupportLevel = CSD_SUPPORT_FLAT;
+        sCSDSupportLevel == CSD_SUPPORT_SYSTEM) {
+        sCSDSupportLevel = CSD_SUPPORT_CLIENT;
     }
 
     // GTK_CSD forces CSD mode - use also CSD because window manager
     // decorations does not work with CSD.
     // We check GTK_CSD as well as gtk_window_should_use_csd() does.
-    if (sCSDSupportLevel == CSD_SUPPORT_FULL) {
+    if (sCSDSupportLevel == CSD_SUPPORT_SYSTEM) {
         const char* csdOverride = getenv("GTK_CSD");
         if (csdOverride && g_strcmp0(csdOverride, "1") == 0) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         }
     }
 
     // Allow MOZ_GTK_TITLEBAR_DECORATION to override our heuristics
     const char* decorationOverride = getenv("MOZ_GTK_TITLEBAR_DECORATION");
     if (decorationOverride) {
         if (strcmp(decorationOverride, "none") == 0) {
             sCSDSupportLevel = CSD_SUPPORT_NONE;
         } else if (strcmp(decorationOverride, "client") == 0) {
-            sCSDSupportLevel = CSD_SUPPORT_FLAT;
+            sCSDSupportLevel = CSD_SUPPORT_CLIENT;
         } else if (strcmp(decorationOverride, "system") == 0) {
-            sCSDSupportLevel = CSD_SUPPORT_FULL;
+            sCSDSupportLevel = CSD_SUPPORT_SYSTEM;
         }
     }
 
     return sCSDSupportLevel;
 }
 
 int32_t
 nsWindow::RoundsWidgetCoordinatesTo()

--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -371,19 +371,19 @@ public:
     LayoutDeviceIntPoint GdkPointToDevicePixels(GdkPoint point);
     LayoutDeviceIntPoint GdkEventCoordsToDevicePixels(gdouble x, gdouble y);
     LayoutDeviceIntRect GdkRectToDevicePixels(GdkRectangle rect);
 
     virtual bool WidgetTypeSupportsAcceleration() override;
 
     bool DoDrawTitlebar() const;
 
-    typedef enum { CSD_SUPPORT_FULL,    // CSD including shadows
-                   CSD_SUPPORT_FLAT,    // CSD without shadows
-                   CSD_SUPPORT_NONE,    // WM does not support CSD at all
+    typedef enum { CSD_SUPPORT_SYSTEM,    // CSD including shadows
+                   CSD_SUPPORT_CLIENT,    // CSD without shadows
+                   CSD_SUPPORT_NONE,      // WM does not support CSD at all
                    CSD_SUPPORT_UNKNOWN
     } CSDSupportLevel;
     /**
      * Get the support of Client Side Decoration by checking
      * the XDG_CURRENT_DESKTOP environment variable.
      */
     static CSDSupportLevel GetCSDSupportLevel();