Blender Git Commit Log

NLA: Indicate position of action-local markers on strips

To make it easier to synchronise timing across multiple strips, if you add
markers locally to an action, these will show up in the NLA strip in the
NLA Editor. These markings can then be used to line up the start/end of
another strip, or even to make sure that the markers from two different
strips end up lining up.

By default, this is turned on, but it can be disabled (via the View menu)
if it adds too much visual noise.