Yes, please add collapsible outlining, as many of your competitors have. Also, outline currently is not really outlining at all because subheadings are numbered identically to main headings. Users can only tell the difference by the difference in tab structure. FOr example, this is not a multilevel outline:
1. Main Heading
1. Subheading
2. Main Heading
1. Subheading
Or am I missing something?