Returns %TRUE if @tag is toggled on at exactly this point.
If @tag is %NULL, returns %TRUE if any tag is toggled on at this point.
Note that if this function returns %TRUE, it means that
@iter is at the beginning of the tagged range, and that the
character at @iter is inside the tagged range. In other
words, unlike [method@Gtk.TextIter.ends_tag], if
this function returns %TRUE, [method@Gtk.TextIter.has_tag
will also return %TRUE for the same parameters.
Returns %TRUE if @tag is toggled on at exactly this point.
If @tag is %NULL, returns %TRUE if any tag is toggled on at this point.
Note that if this function returns %TRUE, it means that @iter is at the beginning of the tagged range, and that the character at @iter is inside the tagged range. In other words, unlike [method@Gtk.TextIter.ends_tag], if this function returns %TRUE, [method@Gtk.TextIter.has_tag will also return %TRUE for the same parameters.