This patch adds the ability to theme the amount of color difference between every other row in the outliner. The option appears underneath the outliner section of the user-preferences, theme. Previously, every other row was hard-coded to be 6 values brighter than the other rows. With this patch, users have more control over the difference in color. For example, a user could choose to remove the color difference between the rows and have a solid background color in the outliner.