You are not logged in.
Happens upon clicking on (or anywhere inside) the e-book-viewer window. Mouse-scrolling down after the click, will instead auto-scroll back up to a previous section. I reported on the Calibre bug-tracker, but it seems to be unique to myself, or at least to archlinux.
If anyone else is running Calibre, would very much like to know if you've experienced this issue. Otherwise I'm not even sure where to start, short of running a debugger and manually stepping through the program execution.
Linux 3.16.2-1
Calibre 2.6.0-1
openbox 3.5.2-6
Offline