From: Calvin Walton <calvin.walton@gmail.com>

Add support for hiding/showing window decorations when maximizing windows.

This patch adds support for hiding and showing window decorations of maximized
windows by manipulating X properties. Most window managers (metacity in
particular) are supported.

This uses code copied from devilspie,
http://burtonini.com/blog/computers/devilspie
to handle switching window decorations on and off.

Devil's Pie is licensed under GPL 2 or any higher version, and is thus
compatible with the GPL 3 that windowapplets is licensed under.

To apply this patch, run (in the windowapplets source directory)
patch -p1 <windowapplets-metacity-notitlebar.patch

diff -ru windowapplets-0.2.5/buttons/windowbuttons.c windowapplets-0.2.5.new//buttons/windowbuttons.c
--- windowapplets-0.2.5/buttons/windowbuttons.c	2010-01-15 11:36:01.000000000 -0500
+++ windowapplets-0.2.5.new//buttons/windowbuttons.c	2010-02-26 21:34:37.712643556 -0500
@@ -24,6 +25,10 @@
  
 #include "windowbuttons.h"
 
+#include <gdk/gdk.h>
+#include <gdk/gdkx.h>
+#include <X11/Xlib.h>
+
 /* Prototypes */
 static void applet_change_background (PanelApplet *, PanelAppletBackgroundType, GdkColor *, GdkPixmap *);
 static void active_workspace_changed (WnckScreen *, WnckWorkspace *, gpointer);
@@ -243,11 +248,76 @@
 	}
 }
 
+static GHashTable *atom_hash = NULL;
+static GHashTable *reverse_atom_hash = NULL;
+
+Atom
+my_wnck_atom_get (const char *atom_name)
+{
+  Atom retval;
+  
+  g_return_val_if_fail (atom_name != NULL, None);
+
+  if (!atom_hash)
+    {
+      atom_hash = g_hash_table_new (g_str_hash, g_str_equal);
+      reverse_atom_hash = g_hash_table_new (NULL, NULL);
+    }
+      
+  retval = GPOINTER_TO_UINT (g_hash_table_lookup (atom_hash, atom_name));
+  if (!retval)
+    {
+      retval = XInternAtom (gdk_display, atom_name, FALSE);
+
+      if (retval != None)
+        {
+          char *name_copy;
+
+          name_copy = g_strdup (atom_name);
+          
+          g_hash_table_insert (atom_hash,
+                               name_copy,
+                               GUINT_TO_POINTER (retval));
+          g_hash_table_insert (reverse_atom_hash,
+                               GUINT_TO_POINTER (retval),
+                               name_copy);
+        }
+    }
+
+  return retval;
+}
+
+static void set_decorations(WnckWindow *window, gboolean decorate) {
+#define PROP_MOTIF_WM_HINTS_ELEMENTS 5
+#define MWM_HINTS_DECORATIONS (1L << 1)
+	struct {
+		unsigned long flags;
+		unsigned long functions;
+		unsigned long decorations;
+		long inputMode;
+		unsigned long status;
+	} hints = {0,};
+	
+	hints.flags = MWM_HINTS_DECORATIONS;
+	hints.decorations = decorate ? 1 : 0;
+	
+	/* Set Motif hints, most window managers handle these */
+	XChangeProperty(GDK_DISPLAY(), wnck_window_get_xid (window),
+		my_wnck_atom_get ("_MOTIF_WM_HINTS"),
+		my_wnck_atom_get ("_MOTIF_WM_HINTS"), 32, PropModeReplace,
+		(unsigned char *)&hints, PROP_MOTIF_WM_HINTS_ELEMENTS);
+}
+
 /* Updates the images according to preferences and the current window situation */
 void updateImages (WBApplet *wbapplet) {
 	WnckWindow *controlledwindow;
 	int i;
 	
+	if (wbapplet->activewindow) {
+		set_decorations(wbapplet->activewindow,
+			!wnck_window_is_maximized(wbapplet->activewindow));
+	}
+	
 	if (wbapplet->prefs->only_maximized) {
 		controlledwindow = wbapplet->currentwindow;
 	} else {