Showing whitespace on minus lines of diff ouput

The colored diff output is quite helpful to show introductions of whitespace.

However, if whitespace has been removed, it's impossible to see in the diff output since whitespace is colorized on '+' lines, but not '-' lines.

I'm looking at diff.c, but wow. Can someone more familiar with this file point me toward how I'd make a patch to colorize whitespace on '-' lines as well?

Thanks,

j.