Comment 9 for bug 172879

db: That's not this bug; that's some completely different bug. Feel free to file it separately (on the debian-installer package).

As for the main meat of this bug, the apt-setup-verify source says that the cancel function is disabled because:

# Option to cancel an action does not currently work:
# - application does not seem to always react to a cancel signal
# - debconf-apt-progress does not exit with code 30 when cancelled
# - even if it did, the exit code would be mangled by in-target
# See also thread http://lists.debian.org/debian-boot/2008/01/msg00094.html

I'd like to fix this for karmic, and will target it appropriately.