To edit a Workbench resource outside the Workbench:
Tip: If you work with external editors regularly, you may want to enable auto-refresh.This can be done by going to the preferences dialog (by choosing the Window >Preferences menu item), drilling down to the General > Workspace preference page, and checking the Refresh automatically option. When this option is enabled, any external changes will be automatically discovered by the Workbench. Depending on the platform this may not happen immediately.
Opening files for editing
Associating editors with file types