I find that, on Arch Linux 0.7, JPilot 0.99.7 has the following odd behaviour:
When I click on the right or left arrowhead in the Day View (to go the next/previous day or year), JPilot jumps 2 days if I choose the Day arrowhead, and 2 years if I choos the Year arrowhead.
This odd behaviour also appears under Slackware 10, but is not present under Gentoo.
I compiled and installed JPilot 0.99.7 from source, enabling GTK2. The same results appear if I use the jpilot package found in extra.
Somewhat solved. I recompiled, but this time without gtk2 support. It works fine that way.