I've had the time to look around.
Interfacing gambas directly to the linux-dvb api seems too hard (to me), and the only tool i found which is able to dump epg information drom dvbt source is tv_grab_dvb, is tiny and can run in background while you are tuned to a dv channel; it outputs an xml which could be parsed and put into a grid.
The problem is that is not that popular and discontinued.
On archlinux it is present only on the aur (which means that is made by users and not reviewed by the official packagers).
Not that it is difficult to grab the svn and compile it, but maybe it could lead to issues for xt7 packagers.
What do you think?
do you know of other tiny external tools?