Unusable X-Axis Times

[twostripe]

When using header/stamps or message receipt times for displaying data, the x-axis becomes impossible to parse in a meaningful way. Times are represented in unix-time that is to say on the order of 1,500,000,000 seconds and display as 1.52824e+09. So it's really unintuitive to know how long a particular sequence is, let alone any given tick mark.

Ideally I'd to

1. Change the x-axis to "shift" the times to staring at 0 (time offset),
2. have a sub-scale (like rqt_plot does), or
3. display the times differently (1.52824e+09 → 10:32:06 PM)

Am I missing something? I fiddled with all the settings I could find.

Thank you.

[skohlbr]

Duplicate of #20, seconding that this would be a very useful feature.