Classes which implement this interface provide methods
that deal with changes in state of Shells.
After creating an instance of a class that implements
this interface it can be added to a shell using the
addShellListener method and removed using
the removeShellListener method. When the
state of the shell changes, the appropriate method will
be invoked.
Shells.After creating an instance of a class that implements this interface it can be added to a shell using the
addShellListenermethod and removed using theremoveShellListenermethod. When the state of the shell changes, the appropriate method will be invoked.