Sets the word-breaking function for the buffer. For information about the arguments to the word-breaking function, see find-wordbreak.
Since the wordbreak function will be called when line breaks are being determined (in a buffer that has a maximum width), there is a constrained set of wx:media-edit% methods that the wordbreak function is allowed to invoke. It cannot invoke a member function that uses information about graphic locations or lines (which are identified in this manual with ``Only valid when the buffer is viewed.''), but it can still invoke member functions that work with snips and item positions.
The standard wordbreaking function uses the buffer's wx:media-wordbreak-map% object to determine which characters break a word. See also wx:media-wordbreak-map% and set-wordbreak-map.
a boxed small integer or null, another boxed small integer or null, and a small integer