Trouble with input field in 6.1 threaded SMS

[TurboFool]

I used to have the nagging problem after upgrading to earlier builds of 6.1 (nueROM) that occasionally the input field in the threaded SMS would suddenly shrink to half-height and not scroll, either, making the second, third, and so-on lines invisible. I'd have to soft-reset to clear it up. It was uncommon enough not to be a big deal, though.

Since updating to the newest version, though (5049), I've noticed it not only more frequently, but it's surviving soft resets, as well.

Does anyone know what causes this and what can fix it?