Why No Comprehensive Dictionary?

Windows programs definitely have spell checking features these days. They're handy. I'm personally a fan of Firefox 2.0's inline spell checking. It's cool.

The problem is that Windows doesn't have an integrated, comprehensive, universal dictionary. So when I'm in Firefox and add a word to the dictionary, it doesn't get added to Word. And vice versa.

What's a guy to do about this? Shouldn't we be able to have a a simple dictionary that all our words go into? Perhaps someone can program something to resolve this dilemma. Maybe Vista solves the problem, but I doubt it. In all likelihood, we'll be stuck adding the same word to multiple dictionaries forever. Wasted time.