diff --git a/ChangeLog b/ChangeLog
index bfffcc9b6..f18b626be 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2008-06-17  Mike Kestner  <mkestner@novell.com>
+
+	* glib/SignalClosure.cs: post back the gvalues after the closure is
+	invoked using a new Update method on GLib.Value.  This only impacts
+	boxed types, since they are the only "value types" passed by ref in
+	the signal marshaling environment.  We can't call set_boxed on the
+	value to update it, since that allocs new memory, we need to marshal
+	the updated struct out to the existing native memory address using
+	g_value_get_boxed.
+	* glib/Value.cs (Update): new update method for writing values to
+	an existing boxed type instance instead of allocating a new native
+	struct.  Fixes #398929.
+
 2008-06-17  Mike Kestner  <mkestner@novell.com>
 
 	* glib/GType.cs (LookupType): traversed referenced assemblies to
diff --git a/glib/SignalClosure.cs b/glib/SignalClosure.cs
index c5738f271..82bed1aa2 100644
--- a/glib/SignalClosure.cs
+++ b/glib/SignalClosure.cs
@@ -134,13 +134,19 @@ namespace GLib {
 
 				SignalArgs args = Activator.CreateInstance (closure.args_type, new object [0]) as SignalArgs;
 				args.Args = new object [n_param_vals - 1];
+				GLib.Value[] vals = new GLib.Value [n_param_vals - 1];
 				for (int i = 1; i < n_param_vals; i++) {
 					IntPtr ptr = new IntPtr (param_values.ToInt64 () + i * Marshal.SizeOf (typeof (Value)));
-					Value val = (Value) Marshal.PtrToStructure (ptr, typeof (Value));
-					args.Args [i - 1] = val.Val;
+					vals [i - 1] = (Value) Marshal.PtrToStructure (ptr, typeof (Value));
+					args.Args [i - 1] = vals [i - 1].Val;
 				}
 				ClosureInvokedArgs ci_args = new ClosureInvokedArgs (__obj, args);
 				closure.Invoke (ci_args);
+				for (int i = 1; i < n_param_vals; i++) {
+					vals [i - 1].Update (args.Args [i - 1]);
+					IntPtr ptr = new IntPtr (param_values.ToInt64 () + i * Marshal.SizeOf (typeof (Value)));
+					Marshal.StructureToPtr (vals [i - 1], ptr, false);
+				}
 				if (return_val == IntPtr.Zero || args.RetVal == null)
 					return;
 
diff --git a/glib/Value.cs b/glib/Value.cs
index d98374210..5190afe2c 100755
--- a/glib/Value.cs
+++ b/glib/Value.cs
@@ -411,6 +411,12 @@ namespace GLib {
 			}
 		}
 
+		internal void Update (object val)
+		{
+			if (g_type_is_a (type, GType.Boxed.Val) && !(val is IWrapper))
+				Marshal.StructureToPtr (val, g_value_get_boxed (ref this), false);
+		}
+
 		[DllImport("libgobject-2.0-0.dll")]
 		static extern void g_value_init (ref GLib.Value val, IntPtr gtype);