window xid tends to be shown in hex in other tools

git-svn-id: https://xpra.org/svn/Xpra/trunk@3128 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/server_source.py

@@ -625,7 +625,7 @@ def _make_metadata(self, wid, window, propname):
             cache["tray"] = window.is_tray()
             try:
                 from wimpiggy.lowlevel import get_xwindow       #@UnresolvedImport
-                cache["xid"] = get_xwindow(window.client_window)
+                cache["xid"] = hex(get_xwindow(window.client_window))
             except:
                 pass
         props = self.do_make_metadata(window, propname)