I was thinking once myself that such functionality could be asked about in the near future, but right now functionality is not there. There is no tree container node selector available now, which you could specify let say inside navigator's properties to expand only that container's section and not whole tree via currently available expandLevel property.
I'll think if it's possible to implement expandSelection property or similar in some next Extlib release. Not sure if several navigators each based on some possible business section could make sense for your situation.