synaptic does not properly handle umlauts (öäü) when searching for packages. To reproduce do * start synaptic * press ctrl-f * enter "Übergangspaket" --> the results window is empty Now try "apt-cache search übergangspaket" in a terminal. It works fine.
Still a bug in squeeze... On the other hand the "quick search" widget properly handles the äöü-Umlauts.
This is still a bug in the current version of synaptic (0.81.2) in unstable.
still a bug in 0.83
this bug seems to be fixed in 0.84.2.