One interesting result was that menus with an even number of items were generally better than those with odd numbers. Also, menus with eight items were especially fast and easy to learn, because of their primary and secondary compass directions. Another result of Kurtenbach's experiment was that, with regard to speed and accuracy, pens were better than mice, and mice were better than trackballs. Monday is on the left, going around counterclockwise to Friday on the right. Wednesday is at the bottom, in the middle of the week, and the weekend floats above on the diagonals.
Today is at the top, so it's always an easy choice.
The NeWS Toolkit code that creats this pie menu is shown in Listing 1. The main disadvantage of pie menus is that when they pop up, they can take a lot of screen space due to their circular layout. Long item labels can make then very large, while short labels or small icons make them more compact and take up less screen space. In a naive implementation, you might use text labels rotates around the center of the pie. This is hard to read without rotating your head, and doesn't even satisfy the goal of minimizing menu size.