It works now! At least with my Kindle3. Probably a matter of Kindle software update during the last year?
This is what I use:
Code:
<idx:orth><b>word</b>
<idx:infl inflgrp="group1">
<idx:iform name="infl1" value="wordform1" />
<idx:iform name="infl2" value="wordform2" />
<idx:iform name="infl3" value="wordform3" />
</idx:infl>
</idx:orth>
It works reliably for context lookup (eg moving cursor to wordform2 will display word in the "bubble").
Not working/potential problems:
1. looking up inflections directly in the dictionary does not work
2. if an inflection exists in dictionary already then only the first definition is displayed (however, even the default Oxford dictionary suffers by this)
3. some problems may appear when replacing an existing dictionary - either by file rewrite or by file with a different name - it seems best to delete the dictionary from Kindle first and then copy the updated one (with inflections/other changes); in order to delete a primary dictionary from Kindle, one needs to change the primary dictionary to other dictionary, do any context lookup with the other dictionary and then the deletion is possible