Subscript in GtkTextView

[Jan <janjakon mail ru>]

Hi.

I would like to show some part of text in GtkTextView like
if it in <sub> xhtml tag.

My code is:

gtk_text_buffer_create_tag(buffer, "<sub>", "rise-set", TRUE, "rise", -3, NULL);

gtk_text_buffer_apply_tag_by_name(buffer, "<sub>", ...);

this didn't work, but if I change properties of "<sub>" tag to, for
example, {"font", "Italic", NULL}.

Problem in rise-set and rise properties, they didn't work, and I can
not understand why.