matplotlib/matplotlib — pull request #1301 by jenshnielsen (2012-09-23 08:38:23+00:00)
Title: Colorbar Add kw arguement to colorbar to reenable edges around faces 

This is an alternative way to resolve problems with white lines in colorbars. It is not enabled by default due to problems with alpha< 1 and colorbar extensions. See #1178 and #1188

This is certainly not the ultimate solution but since it seems difficult to get the viewers fixed this is the simplest workaround that I could come up with.