When creating an index, in order to provide any sort of categorisation, you have to use the 'New Page Reference' box, where you can add multiple categories, See [also], etc.

Currently this box is a fixed size, which makes reusing existing entries (for consistency) very painful, as it involves a lot of scrolling and opening of previous categories (as the categories are collapsed by default every time it's used.

My suggestion would be to make this box both resizable and that it remembers which categories have been expanded previously - for bonus points, it would be great if is remembered the last category entered (and therefore was centred on that category when you next add a reference ...)