gtk.TextView and insert_at_cursor - why doesn't it work?

[emes]

hi all,

i'm developing an application in gtk (+glade). i have to intercept any
modification of gtk.TextView widget contents. using glade, i connected
following signals to callback method:

insert_at_cursor
delete_from_cursor
paste_clipboard

last two work well. after c+p or pressing backspace, my callback is
executed. but the first one doesn't. simple key press and character
input don't invoke my callback. why?

also, pasting with context_menu->paste activates callback but middle-click
paste doesn't.

-- 
michal salaban -|- emes (na) pld-linux.org -|- jabber: emes at jabber.org