user32: Implement BroadcastSystemMessage.
diff --git a/server/protocol.def b/server/protocol.def
index 23aaed5..01d94d2 100644
--- a/server/protocol.def
+++ b/server/protocol.def
@@ -2399,6 +2399,7 @@
 
 /* Open a handle to a desktop */
 @REQ(open_desktop)
+    obj_handle_t winsta;          /* window station to open (null allowed) */
     unsigned int flags;           /* desktop flags */
     unsigned int access;          /* wanted access rights */
     unsigned int attributes;      /* object attributes */