Tag autocomplete should match any word in multi-word tags

May I add the wish that it should match also parts of words (or should I submit a separate request for that one?). This would be useful because in some languages (e.g. German) there are many words like for instance 'kitchen clock' that are written as one (in this case "Küchenuhr").

I'm afraid this will diminish the usefulness of tag autocomplete because the number of matches will be too high. For example, I have a lot of tags, and if it would match within words then when I enter "m" I'll get all tags with letter m, which can be quite a lot. I will have to enter much more letters by hand in order for the autocomplete list to become filtered enough.

You can solve your problem in the following way: since tags are absolutely arbitrary, write your tags with a hypen, like this: kuechen-uhr. As far as I know, German grammar allows this in many cases. And even if not, tags are just what they are - tags)

Although I know such a feature from practice (Jello Dashboard) and find it very useful, you have convinced me that your solution will suffice. ;-)
So 'multi word tag' not only means separated by space but also separated by any non-alphabetic character. Perfect - thanks Chris

Yes, that's exactly what it means. A nice side effect of this is that if you use some tag prefix symbols like "!todo" or "#project" (as tag categorization of sorts), you won't have to enter these symbols any more. Press "t" and "!todo" will be one of the first suggestions ;)