Description of problem:
If categories are related to categories in the category tree for a
content section, the related categories show up in the tree on the
Categories pane; they are (correctly) not shown in the 'Subcategories'
Version-Release number of selected component (if applicable):
Programmatically relate a category from a separate tree to a category
in the standard content section category tree. Check the 'Categories'
tab for the content section.