Program Preferences are accessed from the Window->Preferences menu item.
The Preferences Dialog window
Set optional external editors for certain types of file. For each entry add a file extension (for example, .html, .txt, .doc) and enter the full path to the program that you wish to use to edit files associated with that file extension. If no external editors are specified, the internal text editor is used instead. One use of this would be to associate .xml files with a dedicated XML Editor for editing Metadata files.
Use external viewers for viewing files
When ticked, this option ensures that any content files are viewed in an external
viewer such as the host browser, text viewer, and so on. When unticked, files
are viewed in the internal browser.
Make settings for the Help system.
Set whether to use an external Browser to display Help, and configure the internal Help Server as required.