The left half of history stays blank when running xfce4-cpugraph-plugin-0.3.0 on FreeBSD 6.2-RELEASE AMD64. This does not happen in i386 mode.
Created attachment 973 Bug fix
Confirmed on 64 bit arch linux too. Given the problem in the source code, this bug should reproduce on all OSes following the LP64 model. As far as I know, that would be every OS out there except windows.
Fixed on the master branch.