Okay, first try broke the UI, yay ;D.
Second try, better, and seems to work. Will check that it doesn't sneakily break stuff.
Screenshots, for ref (w/ a custom FT, and on a Touch, for ease of recovery in case things go kablooey [and also because it's the one at the top of the pile
]).
The font used is
SIL Scheherazade (which only ships a regular style, so the bold is synthetic, and happens to be a good testcase, since it renders Latin scripts horribly [w/ default ft settings (ie. bci, I suspect the autohinter would take better care of it]).
(First screenshot is w/ PubFont, second is Scheherazade [through fallback mechanism]).
EDIT: Nope, false alarm.
I'll merge this in the Fonts Hack once I've checked it doesn't break anything
.