Perm URL with updates: http://xahlee.info/linux/linux_postfix_install_popup.html
When installing postfix, it does a annoying popup. Here's a screenshot:
Programs shouldn't do this, because it interrupts installation.
For example, this happened when i'm installing emacs dependencies by
sudo apt-get build-dep emacs23. 〔☛ Building Emacs on Linux — a Guide〕 I wasn't even consciously installing postfix. You go for a coffee, expecting things will be done when you come back, but instead, you get this popup stuck on your screen.
Another software that does this is MySQL.