Returns a list of TextTag that are toggled on or off at this point.
(If toggled_on is true, the list contains tags that are toggled on.) If a tag is toggled
on at this, then some non-empty range of characters following this has
that tag applied to it. If a tag is toggled off, then some non-empty range following this does not have
the tag applied to it.
| this |
an iterator |
| toggled_on |
true to get toggled-on tags |
|
tags toggled at this point |