twitter/bootstrap — pull request #5970 by bisrael (2012-11-21 03:54:38+00:00)
Title: Add 'fully' class to post-transitioned collapse regions

Add .fully class to .collapse regions upon the transition completing.
The .fully class, when present alongside .in, undoes the
overflow:hidden required for keeping the innards of .collapse regions
from spilling out. We can remove this when the region is completely
open without much negative side-effect.

Fixes #3601