In ImageJ versions previous to 1.38k under linux, the Help>ImageJ Web Site and Help>Online Docs… commands run the Netscape browser to open the ImageJ website.
If Netscape is not installed, these commands do not work. One can solve this by providing a symbolic link to the command that launches the installed browser. For example:
ln -s /usr/bin/firefox /usr/local/bin/netscape
or
ln -s /opt/kde3/bin/konqueror /usr/local/bin/netscape\\
Version 1.38k resolves this issue and is able to launch one of the following browsers if installed (in this order): netscape, firefox, konqueror, mozilla, opera, epiphany or lynx.
If you have a preference for a particular browser, you can use the trick of making a symbolic link to “netscape” as outlined above.