Gnome screen lock "Switch User" button does not work in vnc session.

Issue

• Unable to switch user using Switch User button in vnc session.

  Steps to reproduce the issue:

  • Configure VNC based on xinetd with XDMCP for GDM.
  • Connect to remote gnome session using vncviewer.
  • Press Switch User button, in VNC client
  • After pressing the Switch User button, VNC client screen gets black for ~5 seconds. After the black screen, the screen lock comes back.

• all vnc server sessions are running as nobody user in this case, and not as user logged in:

  # ps -ef|grep vnc
  nobody    561429    2979  0 11:01 ?        00:00:03 Xvnc -inetd -once -query localhost -SecurityTypes=VeNCrypt,TLSnone 
  -geometry 1280x1024 -depth 24 -extension XFIXES