Participant list sidebar is changing its size
Bug description
Participant list sidebar is changing its size when Maximizing/Restoring the MUC window.
Steps to reproduce
Maximize & Restore your MUC window.
Software versions
OS version: Salix OS 13.1.2 (Slackware 13.1.0 based)
GTK version: 2.18.9
PyGTK Version: 2.16.0