method private exec html_start html_end () =
let (i1,i2) = wview#buffer#selection_bounds in
let s = i1#get_text ~stop: i2 in
match s with
"" ->
wview#buffer#insert (html_start^html_end)
| _ ->
ignore (wview#buffer#insert ~iter: i2 html_end);
ignore (wview#buffer#insert ~iter: i1 html_start);
wview#buffer#place_cursor ~where: i2