(From personal stash of bugs - since early 2.5 versions)
F-Curve colors get applied only on Graph Editor "refresh()". In some cases, undo
was reverting back to a state where the colors had not yet been set. In these
cases, there would be no refresh() after that undo (until expanding a channel or
some other similar action), resulting in "black F-Curves" appearing. So, now we
force such an update after undo to ensure that the curves never display black.
(Noticed while investigating another bug for Mango related to
CLIP_OT_constraint_to_fcurve not sending notifiers required when new F-Curves
are added)
44ca0a4328