Revert "don't use GLib directly"

This reverts commit bc8bf26.

xpra/server/mixins/child_command_server.py

@@ -11,6 +11,8 @@
 from time import monotonic
 from subprocess import Popen
 
+from gi.repository import GLib
+
 from xpra.platform.features import COMMAND_SIGNALS
 from xpra.child_reaper import getChildReaper, reaper_cleanup
 from xpra.os_util import (
@@ -72,7 +74,7 @@ def __init__(self):
         #even if __init__ is called multiple times:
         if not getattr(self, "late_start_requested", False):
             self.late_start_requested = True
-            self.idle_add(self.late_start)
+            GLib.idle_add(self.late_start)
 
     def late_start(self):
         def do_late_start():