There is no easy way for an end user to make the program use more than 12 different colors for the density plots.
However, there is no fundamental reason that the program couldn't be changed to use more colors--it would be relatively easy to change the source so that there were, for example, 16 colors instead of 12. I just thought that things looked too busy with a lot more colors. I suppose that I could change the code so that there is more of a continuous-looking distribution of colors if there is a really strong feeling about it.
Dave.