diff --git a/xpra/server/shadow/gtk_shadow_server_base.py b/xpra/server/shadow/gtk_shadow_server_base.py
index 5a8b613810..46eac019c0 100644
--- a/xpra/server/shadow/gtk_shadow_server_base.py
+++ b/xpra/server/shadow/gtk_shadow_server_base.py
@@ -257,11 +257,11 @@ def refresh_window_models(self):
             return
         xid_to_window = {}
         for window in windows:
-            xid = window.get_property("xid")
+            xid = window.get_id()
             xid_to_window[xid] = window
         sources = self.window_sources()
         for wid, window in tuple(self._id_to_window.items()):
-            xid = window.get_property("xid")
+            xid = window.get_id()
             new_model = xid_to_window.pop(xid, None)
             if new_model is None:
                 #window no longer exists:
diff --git a/xpra/x11/shadow_x11_server.py b/xpra/x11/shadow_x11_server.py
index 02de7ba65d..0f96d8d92e 100755
--- a/xpra/x11/shadow_x11_server.py
+++ b/xpra/x11/shadow_x11_server.py
@@ -144,6 +144,9 @@ def __init__(self, root_window, capture=None, title="", geometry=None):
         except Exception:
             self.xid = 0
 
+    def get_id(self):
+        return self.xid
+
     def __repr__(self):
         return "X11ShadowModel(%s : %24s : %s)" % (self.capture, self.geometry, self.xid)