[Hampshire] Restarting upgraded packages

I often wonder how important it is to restart a newly upgraded
package.

Firefox comes up with a warning to restart any running instances
after an upgrade as does a kernel upgrade.

But how about things like xserver-xorg-core or konsole (2 packages
upgraded this morning), do they just run the upgraded package
seamlessly?

--
John Lewis
Debian Linux with Geneweb genealogy application