A DESCRIPTION OF THE REQUEST :

The Webstart-Class LaunchDownload has two small unsightly issues:
1.) Some undersynchronization when accessing thread-global static variables
2.) Busy waiting for available updates: while (_numThread > 0 ) { if(..){break;} ....}

I've refactoted the code a bit to use a seperate protected class, which now also encapsulates the thread-shared-variablesm instead of an anonymous inner class used before. This encapsulates the inter-thread access, and hopefully will lead to less problems when implementing future additions.

JUSTIFICATION :
1.) Undersynchronization is dangerous, it could happen that it waits to long because the value is not updated correctly.
2.) Busy waiting is ugly in general ;)