after-change-style in text%
Called after the style is changed for a given range
(and after the display is refreshed; use
on-change-style and
begin-edit-sequence to avoid extra refreshes when
after-change-style modifies the editor).
See also
can-change-style? and
on-edit-sequence.
No internals locks are set when this method is called.
( -> void
send a-text after-change-style start len)
start : exact non-negative integer
len : exact non-negative integer