As the "pure Java" way of launching new browser windows, the showDocument
method, is rendered nonfunctional in more and more environments by popup
blockers, developers whose Java applets are digitally-signed have been able
to get the same functionality by using Runtime.exec calls.

On the Macintosh one can open a new Firefox window regardless of the
location of Firefox as follows:

Runtime.getRuntime().exec(new String[] {"open", "-a", "Firefox.app",
url.toString()});

On Windows it is possible to launch Internet Explorer or Firefox by assuming
a particular location as follows:

Runtime.getRuntime().exec("\"C:\\Program Files\\Internet
Explorer\\IEXPLORE.EXE\" " + url);
Runtime.getRuntime().exec("\"C:\\Program Files\\Mozilla
Firefox\\firefox.exe\" \"" + url + "\"");

The problem is that these forms depend on the browser files being in their
usual locations.  Is there a way of launching the browsers in a
location-independent way using Java code on Windows, by analogy to what
works on the Macintosh even if Firefox is not in its usual location in the
/Applications folder?

NOTE:  We use new browser windows to display further information on outside
Web sites such as articles about a diagnosis being considered by the user.
Using a new browser window allows us to do so without destroying our applet
or trying to shoehorn someone else's Web page into a frame on the same page
as our applet.