Slavek,
I don't know what name change did this, but kdesktop tries to load 'tdmtsak'. It should be loading 'kdmtsak'. Here is the error generated in .xsession-errors:
[kdesktop] SAK driven secure dialog is not available for use (retcode 6). Check tdmtsak for proper functionality.
I checked and the kdmtsak binary is there:
18:52 tdesru:~> l /opt/trinity/bin/*sak* -rws--x--x 1 root root 28209 Aug 12 01:21 /opt/trinity/bin/kdmtsak -rwxr-xr-x 1 root root 24113 Aug 12 01:46 /opt/trinity/bin/tsak