As a quick follow-up, it's actually not inserting the `space` character, but a different character that appears as a single space. It shows up as a diamond with "show invisibles" enabled (whereas `space` remains invisible). It actuall turns out to be hex '\x1100', vs. space which is '\x2000'. It's also the same character that is inserted after a single press of ctrl-opt-q (while it requires two sequential presses of ctrl-q).
Interestingly, ctrl-q also seems to be a trigger for some alternate input mode in some apps in which it works. Although this doesn't strictly work in TextMate, in NSTextAreas all manner of keys wind up generating odd characters when they've been primed by a single-press of ^q, e.g. the arrow keys (left, right, up, down) produce \x2f7, \x3f7, \xf7, \x1f7.
Clearly *some* editing mode or something is being triggered on ctrl-q, but I can't for the life of me figure out what or where it is (I certainly haven't found ^q clearly referenced in any of the keybinding dictionaries on my disk).
Still baffled and frustrated.
Thanks. -jrk