Returns a list of `GtkTextTag` 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 |