This is done as a preventative measure in order to save memory. For the Macintosh, this occurs when there is more than one stopped applet. For each new applet started somenumberof stopped applets are pruned until the above threshold is reached, or until no more stopped applets can be found. This means that if a page contains more than the allowable number of applets, or if several opened windows together contain more than the allowable number of applets, there can be more than that number of applets running. However, as soon as a page containing applets is pushed in the history, those applets will be pruned until the allowable number is reached.
Applet lifetime is very much tied to the notion of history.
Typing a ' 0 ' will disable debugging. In Netscape Navigator version 3.02 or greater, you can also type ' h ' to get a list of other applet debugging options.