The missing link to get things to work is a mapping from the “lirc-codes” to functions of VDR. In /etc/vdr there is a symlink “remote.conf” to a missing(!)  file located in /var/lib/vdr/remote.conf. That file will contain the required mapping. For me it was enough (sometimes) just to create the missing file (touch /var/lib/vdr/remote.conf – take care that vdr owns the file), restart vdr( /etc/init.d/vdr restart) and start the video output (for my setup: xinit -e vdr-sxfe -f). Now some teaching dialogue will (most likely) appear that tells you to press buttons in some sequence (press 1, press 2, …) and that remembers the received “lirc-codes”. If you went through this and later edit the mapping file you’ll have something like this:

LIRC.Up Up
LIRC.Down Down
LIRC.Menu Home
LIRC.Ok OK
LIRC.Back Back
LIRC.Left Left
LIRC.Right Right
LIRC.Red Red
LIRC.Green Green
LIRC.Yellow Yellow
LIRC.Blue Blue
LIRC.0 Zero
LIRC.1 One
LIRC.2 Two
LIRC.3 Three
LIRC.4 Four
LIRC.5 Five
LIRC.6 Six
LIRC.7 Seven
LIRC.8 Eight
LIRC.9 Nine
LIRC.Info More
LIRC.Play Play
LIRC.Pause Pause
LIRC.Stop Stop
LIRC.Record Record
LIRC.FastFwd Forward
LIRC.FastRew Rewind
LIRC.Next Skip
LIRC.Prev Replay
LIRC.Power Power
LIRC.Channel+ ChanUp
LIRC.Channel- ChanDown
LIRC.Volume+ VolUp
LIRC.Volume- VolDown
LIRC.Mute Mute
LIRC.Schedule KEY_TIMESHIFTING
LIRC.Channels DVD
LIRC.Timers LiveTV
LIRC.Recordings Guide

It is also possible, just to copy and paste the listing above to the mapping file. Just restart vdr and be happy that the remote will work now for VDR.