David, NumberFormat does not seem to suit my need. I have a stackedAreaXY plot, where X is time in seconds. Instead of seeing ------------------------- 1 2 3 4 5 6 7 8 on my x-axis, I like to see ------------------------------------------------------------------------- 00:00:01 00:00:05 00:00:10 Can I override the function that do the x-axis labeling? Thanks, Tim