I know the F-curve system, particularly how channels are selected in the F-curves Editor, is under refactoring, but I can’t find any reference to this particular question.
When applying an F-curve modifier, in this case Cycles, so I can repeat an animation without having to duplicate keyframes, it is only applied to the Active Keyframe. After a lot of time spent diddling about with figuring how the “Active Keyframe” is determined in the Editor (it has to do with not only which one you click on, but also on which ones are “higher” on the list and already clicked on but which are hidden – this needs serious reconsideration), I then discovered that modifiers can only be applied one F-curve at a time.
Well enough for a simple case of object animation or a simple armature but my character has hundreds and hundreds of keyable bones. What a huge waste of time to not be able to apply a Cycles modifier to the entire keying set at once! Is there any way short of spending a week writing and troubleshooting a Python script (OK, so I’m not the world’s speediest scripter ;)) that this can be done?
The trouble seems to be that the F-curve is only applied to the Active F-curve, and only one F-curve can be active at one time. Why not applied to all selected F-curves?
EDIT: On top of it all, there seems to be a bug that will cause unselected F-curves higher in the list than one you are trying to select to become designated, and selected, as the Active F-curve when you make a selection, any selection. This means that you have to un-do earlier modifier assignments in order to make a new one, because if the algorithm reaches an F-curve with the modifier already applied (and it seems to read the entire list from top down each time), it quits with an error message, and nothing gets done.
Which seems to describe this part of the animation system very well – it’s a good way to get nothing done!
EDIT^2: An now, to really top things off, trying to add an F-curve modifier to one channel caused Blender to suddenly crashquit and deep-six about an hour and a half of dicking around with these &^%@$!) F-curves, when all I want to do is have my animation repeat a few times. Way, way, way too complicated and buggy for any kind of reasonable work flow.