Please see index_on_firefox.png and index_on_htmlhelp.png. "and" is
inactive item not linking to any page, but this item is not shown in
htmlhelp.

I hope this can be fixed by attached patch. I learned this technique to
create inactive link from HTML Help Workshop document.

http://msdn.microsoft.com/en-us/library/ms669985.aspx
http://go.microsoft.com/fwlink/?linkid=14581 # direct link to HelpDocs.zip

And please enter keyword "index files, creating inactive links".

This describes second bug.

When multiple target was bound to same keyword, only first target could
be browsed.

In index_on_firefox.png, we can see "operator, [1], [2]". This [?] means
multiple targets are linked to same keyword and we can browse each
target in firefox. But from htmlhelp, we can only browse first target.

Attached patch "sphinx_multiple_targets.patch" will enable us to select
each targets in popup dialog. (They all have same title, I think it's
useless though)

Please apply this patch after applied sphinx_inactive_index_item.patch.

Sorry, I found another problem on html help about case sensitivity.
Pleas e pend my patch...

Even if two bugs are solved, one weird problem remains. See
binary_index.png. "unicode, built-in function" should go under "unicode"
node, but it goes under "Unicode" node. This happens because  sitemap
format (hhk file) is *case insensitive*, and if binary index is turned
on, indexes are sorted and *merged* automatically.

I hope attached sphinx_index.patch will fix this problem. You don't have
to apply previous two patches. It should be applied to tip cleanly.

# Turning off binary index causes some change to look&feel of index
pane. For example, if you click inactive item, nothing happens instead
of alert dialog.

Okay, I applied your latest patch as changeset 970452b02e2e. Thanks!