can-change-style? (augmentable only) in text%

Called before the style is changed in a given range of the editor. If the return value is #f, then the style change will be aborted.

The editor is internally locked for writing during a call to this method (see also Locks). Use after-change-style to modify the editor, if necessary.

See also on-change-style, after-change-style, and on-edit-sequence.

• (send a-text can-change-style? start len) -> boolean
     start : exact non-negative integer
     len : exact non-negative integer