Lightning is presently far less than optimal as an outliner because only the content of a single node can be exported to a word processor. Not even a node title travels with it.
The program would be far more useful if it could be used as an outliner and node structures be exported to WordPerfect as an outline including node titles marked with table of contents tags. That would enable folks to easily convert content stored in multiple nodes of Lightning to a WordPerfect document ready for generation of a table of contents. This might require adding a setting to WordPerfect for a default outline style to use when receiving an outline exported by Lightning. And WordPerfect itself would be far more useful were there an option to easily add TOC marking codes to a given outline style. It is a less-than-user-friendly process at this point to add TOC marking codes to a range of outline heading level styles.
There is a wonderful resource for outliner development at http://www.atpm.com/Back/atpo.shtml (.) Written by an outliner developer, the site thoroughly explores outliner features in use in the world. Lots of food for creative juices.
Finally, I call to your attention that the W3C yesterday issued WICD Full 1.0 profile as a candidate recommendation. This fleshes out the W3C's work around the Compound Documents by Reference Framework, adding a methodology for converging rich desktop editors with the Web and mobile devices. The Framework itself a rock-solid interoperability framework. For relevant links, see http://www.w3.org/2004/CDF/ (.) This is a golden opportunity for Lightning to be positioned as a light-weight desktop editor fully compatible with mobile devices and the desktop.