http://bugs.winehq.org/show_bug.cgi?id=23622
--- Comment #29 from Owen Rudge owen@owenrudge.net 2011-02-24 15:34:18 CST --- (In reply to comment #28)
I don't believe thats possible, the icons in the left view are internal to the help viewer. From what I have seen, there are only three possible icons, a book, an open book and one that is nothing but a "?". A minor issue, but makes end users think something is broken.
According to the MS docs included in the HTML Help Workshop, there are 8 predefined images, but contents files can include custom image strips, with up to 42 user-defined icons. Implementing support for custom strips is a bit more work, but it would be relatively trivial to draw the default icons and add in support for them.