If I launch the Java Control Panel (perhaps via javaws -viewer) and change the proxy server using General -> Network Settings -> Use proxy server, then click OK in the Network Settings dialogue, I would expect that if I think launch the JavaWS viewer using General -> Temporary Internet Files -> View it would use the proxy server I just set. So for example if I do Run Online, it should look for an update using the new proxy server. But in fact it does not -- the old proxy server continues to be used until I exit the Java Control Panel and restart it.
This used to work in Tiger, because the order of operations was inverted. I.e. you opened the control panel from within the JavaWS viewer, changed the network settings, then closed the control panel, which saved the settings. Now that the JavaWS viewer is opened from the control panel, the point at which the settings are saved should be rethought.