Fixed some long-standing bugs with DopeSheet and NLA Editor main views not being properly lined up with their channels, and/or showing an incorrect scrollbar.
This fixes#20759, and probably a few other reports about similar issues that might've cropped up.
NOTE:
- probably a version bump might be needed after this, to avoid problems on durian animation files?
- the default .b.blend needs updating again, since the saved config there doesn't get updated (or doesn't here, when using load factory settings)
f84f96aee5