Hello,
After seeking the sources and libs, I still have not found the line where you hide each 2nd x-axis-label.
I want all x-axis labels to be visible and by default, the opengraphcharts do so; but not in piwik.
In the json code which is read by the SWFs. then 2nd, 4th, 6th, … x-axis label is empty 
Please help, thanks