Add a tag to the table. The tag is assigned the highest priority in the table.
@tag must not be in a tag table already, and may not have the same name as an already-added tag.
a #GtkTextTag
%TRUE on success.
See Implementation
Add a tag to the table. The tag is assigned the highest priority in the table.
@tag must not be in a tag table already, and may not have the same name as an already-added tag.