When a pie's labels don't fit within its container, the pie is redrawn
with a smaller radius until the labels fit, or a fixed number of retry
attempts are exhausted. The redraw flag was not reset on success,
however, which prevented the pie from being redrawn again after a resize
or update.
When a slice equals (or comes close enough that it is equal in
floating-point representation) 100% of the pie, it was no longer drawn
by Excanvas. This is because of a long-standing issue where VML won't
draw an arc whose begin and end are the same. Rather than some hack,
like adding/subtracting a small value, we'll simply draw two arcs for
every slice, with each covering half of the slice's angle.
Substitute zero when .width() returns undefined, since legendWidth is
used in numeric calculations that break when it is undefined. This
became a problem with the release of jQuery 1.8.0, which returns
undefined instead of null when an element doesn't exist. This was fixed
in 1.8.1, but this is good practice anyway.