Question about chart colors

   I have just started using gkrellm on my systems and have a question about
display colors on the charts. I looked on the web site without seeing an
explanation so if this information is there, please point me to it.

   On one host with the default theme, the CPU usage displays in cyan while
the disk usage displays in orange. But, now and then, I see cyan lines in
the disk activity display on top of, of adjacent to, orange lines.

   I assume the color differences have meaning and I'd like to understand
what they mean.

   Looking forward to learning.

Regards,

Rich