I found that quite a number of buttons gave "not implemented" error.

1) For HTML pages, they CAN be included into the jar file. I did make applications that displays help documents that are included in jar archive.

2) I recommend that you do not use constant class for localization/internationalization. In fact, the Java i18n approach uses the class MessageFormat as well as .properties files that gives a unique name to each constant string/pattern throughout the application.

You can find sample code for the above points from sun's web site. I did both before, so I'm pretty sure they are operational and they are indeed convenient.

1) This problem has similar solution to the internationalization problem, supprisingly--use java resource bundles!
jEditorPane.setPage(YourClass.class.getResource("relative_path/file.html"));


2) The problem of your approach of contant class: no one can customize your application for a new language without knowning Java! Instead, if you do it using ResourceBundle + MessageFormat, the correct resource (.properties file) can be automatically loaded for the user system's default locale, and the correct language will be used automatically. Also, someone else can localize your application without a simple text editor without using any JDK at all.

For simple searching, I suppose keyword matching is reasonably good in the context. You might just need to optimize your algorithm.