diff --git a/gfx/src/nsThemeConstants.h b/gfx/src/nsThemeConstants.h
index 1b8f6687351..f66ec6562a2 100644
--- a/gfx/src/nsThemeConstants.h
+++ b/gfx/src/nsThemeConstants.h
@@ -251,3 +251,7 @@
 #define NS_THEME_WINDOW_BUTTON_RESTORE                     239
 #define NS_THEME_WINDOW_BUTTON_BOX                         240
 #define NS_THEME_WINDOW_BUTTON_BOX_MAXIMIZED               241
+
+// moz-apperance style used in setting proper glass margins
+#define NS_THEME_WIN_EXCLUDE_GLASS                         242
+
diff --git a/layout/base/nsDisplayItemTypes.h b/layout/base/nsDisplayItemTypes.h
index 1acdb21e134..97fbd491094 100644
--- a/layout/base/nsDisplayItemTypes.h
+++ b/layout/base/nsDisplayItemTypes.h
@@ -99,6 +99,7 @@ enum Type {
   TYPE_VIDEO,
   TYPE_WRAP_LIST,
   TYPE_ZOOM,
+  TYPE_EXCLUDE_GLASS_FRAME,
 
 #if defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF)
   TYPE_REFLOW_COUNT,
diff --git a/layout/style/nsCSSKeywordList.h b/layout/style/nsCSSKeywordList.h
index d70d3fd4818..57eafaa7c45 100644
--- a/layout/style/nsCSSKeywordList.h
+++ b/layout/style/nsCSSKeywordList.h
@@ -583,6 +583,7 @@ CSS_KEY(-moz-window-button-restore, _moz_window_button_restore)
 CSS_KEY(-moz-window-button-box, _moz_window_button_box)
 CSS_KEY(-moz-window-button-box-maximized, _moz_window_button_box_maximized)
 CSS_KEY(-moz-mac-unified-toolbar, _moz_mac_unified_toolbar)
+CSS_KEY(-moz-win-exclude-glass, _moz_win_exclude_glass)
 CSS_KEY(alphabetic, alphabetic)
 CSS_KEY(bevel, bevel)
 CSS_KEY(butt, butt)
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index 0a3b59e05a5..0f21bbd3f52 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -579,6 +579,7 @@ const PRInt32 nsCSSProps::kAppearanceKTable[] = {
   eCSSKeyword__moz_window_button_restore,     NS_THEME_WINDOW_BUTTON_RESTORE,
   eCSSKeyword__moz_window_button_box,         NS_THEME_WINDOW_BUTTON_BOX,
   eCSSKeyword__moz_window_button_box_maximized, NS_THEME_WINDOW_BUTTON_BOX_MAXIMIZED,
+  eCSSKeyword__moz_win_exclude_glass,         NS_THEME_WIN_EXCLUDE_GLASS,
   eCSSKeyword_UNKNOWN,-1
 };