Class for tracking the current and previous WindowState and PortletMode for
a PortletWindow. The previous mode and state fields are automaticly updated
when the current mode and state are updated. The getters/setters are
synchronized since setting the previous and current is not an atomic
operation.
author: Eric Dalquist edalquist@unicon.net version: $Id: PortletWindowStateInfo.java 35884 2005-06-07 00:01:07Z edalquist $