How to lock packages to protect them of being removed during upgrades?

[Ralf Mardorf <ralf.mardorf@alice-dsl.net>]

Hi :)

how can I find out which packages I need to lock against upgrading, to
avoid that Synaptic will remove other packages I need? Isn't there a way
to lock packages against removing?

Usually there only will be some packages that will be upgraded, hence
it's easy to find out which packages I need to lock against upgrading,
but now there are to many packages, that will be upgraded.

I already made a backup of the current Debian and locked several
packages, anyway, I'm unable to upgrade, since I would lose needed
development packages.

Regards,

Ralf