Independant from the directory search path issue i just filed in #991253, the bundled hunspell fails for me on any word, marking them all as wrong. After adding some defines/debugs to spellchecker (basically, turning on HUNSPELL_WARNING, DEBUG_SPELLCHECKER, DEBUG_bsmedberg and DEBUG_INLINESPELL), it loads the .aff files fine (ie says "Adding dictionary:en-US") but later on fails on the dic file and spits "error: empty dic file" from http://mxr.mozilla.org/mozilla-release/source/extensions/spellcheck/hunspell/src/hashmgr.cpp#421. I see all words/dom strings being passed to hunspell, but since it failed to open/find the actual dic, all words are considered as wrong. Looking with strace/ktrace, it seems ffx doesnt even try to open the .dic file, only the .aff file is opened. Interestingly, if i build with a systemwide hunspell 1.3.2 using --enable-system-hunspell, spellchecker works (ie doesnt underline _all_ words in red like the bundled hunspell does) Guess i'll have to add some debug printfs to understand why the bundled hunspell chokes.

Where did you get the .dic file from?

It behaves the same with the en-US dict bundled within ffx or the mozilla-dicts packages extracted from the xpis on AMO - the same dicts work with system-hunspell.