Presentation of index items

[bohungi]

In read mode, index items can be nested, and the tree of indices is presented in expanded form. An ebook will easily have hundreds of index items, and presenting those in expanded form by default will be less efficient than presenting them in collapsed form.

Possible solutions:

1. present nested index items in collapsed form by default,
2. offer a button "Collapse all"
3. Do both: 1. and 2.
4. Other???