on-new-box in editor:basic-mixin

Creates and returns a new snip for an embedded editor. This method is called by insert-box.

• (send an-editor:basic-mixin on-new-box type) -> (instance editor-snip%)
     type : (union 'pasteboard 'text)

  Creates instances of pasteboard:basic% or text:basic% instead of the built in pasteboard% and text% classes.