In a pie chart, long labels stick out a lot. It should be possible to wrap
labels to make them stick out less. This is especially important when the label
is placed "inside" its pie slice, to make it better fit into the slice, but
would also improve long labels placed "outside".

It should be possible to manually wrap the labels.

Automatic wrapping could be done reasonably well, for example by iteratively
moving an imaginary edge and wrapping labels that cross it, until there remains
too little space between labels.

For a label placed "inside" its slice, you have two edges (at an angle to each
other) against which the label will fit.