Synaptic 'rollback' function?

[Chanchao]

I just installed a KDE application on Ubuntu. Of course it required a
big pile of KDE libraries and other packages. 

Suppose I want to uninstall that application, is there an easy way of
getting rid of all those packages it depended upon?

Or in other words, would it be possible to set/save the current state of
all installed packages, and then roll back to that savepoint?

Cheers,
Chanchao