matplotlib/matplotlib — pull request #734 by mdboom (2012-03-01 15:54:05+00:00)
Title: Further refinement of marker placement and snapping.

Since paths (particularly marker paths, which are centered at (0, 0)) can cross the origin, it is better to round using floor() than round() (which rounds toward 0).

Markers are placed correctly with respect to the snapping of the axes that contains them.

The clipbox calculation has been adjusted to match the snapping of the axes rectangle.