#799: make sure we can use the pid as reference if the leader xid is …

…not specified (the leader_id is never None!)

git-svn-id: https://xpra.org/svn/Xpra/trunk@8603 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client/gtk2/client.py

@@ -366,7 +366,7 @@ def get_group_leader(self, metadata, override_redirect):
             return group_leader_window
         reftype = "xid"
         ref = leader_xid
-        if ref is None:
+        if ref<0:
             reftype = "pid"
             ref = pid
         if ref is None: