prevent python3 error "unorderable types": ensure we have non-zero in…

…ts before comparing them

git-svn-id: https://xpra.org/svn/Xpra/trunk@6205 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client/ui_client_base.py

@@ -731,7 +731,7 @@ def update_focus(self, wid, gotit):
                 self.window_ungrab()
                 self.do_force_ungrab(self._window_with_grab)
                 self._window_with_grab = None
-            if self._focused!=wid and wid>0 and self._focused>0:
+            if wid and self._focused and self._focused!=wid:
                 #if this window lost focus, it must have had it!
                 #(catch up - makes things like OR windows work:
                 # their parent receives the focus-out event)