XFCE disables the system decorations if there's an xshape set. So

chrome/browser/gtk/browser_window_gtk.cc

Index: chrome/browser/gtk/browser_window_gtk.cc
diff --git a/chrome/browser/gtk/browser_window_gtk.cc b/chrome/browser/gtk/browser_window_gtk.cc
index 3d5743318950ae5ff02b952e07d5fae1a2590707..1da4fd565334e6f20a87aed53818310366551686 100644
--- a/chrome/browser/gtk/browser_window_gtk.cc
+++ b/chrome/browser/gtk/browser_window_gtk.cc
@@ -1118,12 +1118,16 @@ void BrowserWindowGtk::UpdateWindowShape(int width, int height) {
     gtk_alignment_set_padding(GTK_ALIGNMENT(window_container_), 1,
         kFrameBorderThickness, kFrameBorderThickness, kFrameBorderThickness);
   } else {
-    // Disable rounded corners.  Simply passing in a NULL region doesn't
-    // seem to work on KWin, so manually set the shape to the whole window.
-    GdkRectangle rect = { 0, 0, width, height };
-    GdkRegion* mask = gdk_region_rectangle(&rect);
-    gdk_window_shape_combine_region(GTK_WIDGET(window_)->window, mask, 0, 0);
-    gdk_region_destroy(mask);
+    if (use_custom_frame_.GetValue()) {

[Evan Stade, 2009/07/08 23:02:39]

can you put the first line of the desc. as a comment here?

+      // Disable rounded corners.  Simply passing in a NULL region doesn't
+      // seem to work on KWin, so manually set the shape to the whole window.
+      GdkRectangle rect = { 0, 0, width, height };
+      GdkRegion* mask = gdk_region_rectangle(&rect);
+      gdk_window_shape_combine_region(GTK_WIDGET(window_)->window, mask, 0, 0);
+      gdk_region_destroy(mask);
+    } else {
+      gdk_window_shape_combine_region(GTK_WIDGET(window_)->window, NULL, 0, 0);
+    }
     gtk_alignment_set_padding(GTK_ALIGNMENT(window_container_), 0, 0, 0, 0);
   }
 }