Added global management of user handles in the server.
Very preliminary support for shared window handles.

diff --git a/server/request.h b/server/request.h
index 3187fe5..97bc21e 100644
--- a/server/request.h
+++ b/server/request.h
@@ -188,6 +188,11 @@
 DECL_HANDLER(wait_named_pipe);
 DECL_HANDLER(disconnect_named_pipe);
 DECL_HANDLER(get_named_pipe_info);
+DECL_HANDLER(create_desktop_window);
+DECL_HANDLER(create_window);
+DECL_HANDLER(link_window);
+DECL_HANDLER(destroy_window);
+DECL_HANDLER(get_window_info);
 
 #ifdef WANT_REQUEST_HANDLERS
 
@@ -317,6 +322,11 @@
     (req_handler)req_wait_named_pipe,
     (req_handler)req_disconnect_named_pipe,
     (req_handler)req_get_named_pipe_info,
+    (req_handler)req_create_desktop_window,
+    (req_handler)req_create_window,
+    (req_handler)req_link_window,
+    (req_handler)req_destroy_window,
+    (req_handler)req_get_window_info,
 };
 #endif  /* WANT_REQUEST_HANDLERS */