The bug has been opened on https://bugs.launchpad.net/ubuntu/+source/evolution/+bug/103022

"Binary package hint: evolution

I'm not sure if this really qualifies as a bug, but here goes. This happens in Edgy, not sure if it still holds for Feisty.

At the bottom left of my evolution window are the icons for mail, contacts, calendar, memos, and tasks in that order. However, the default keyboard shortcuts for switching to these windows (listed under View -> Windows) are respectively

ctrl-1, ctrl-2, ctrl-3, ctrl-5, ctrl-4

So, even though the memos icon comes before the tasks icon, ctrl-4 gives the tasks window and ctrl-5 the memos window. It seems that since the memos icon is fourth on the list of icons, ctrl-4 should give memos and ctrl-5 tasks. Or, the location of the memos and tasks icons should be swapped."