Just finally figured this one out! It's possible to add an entry to KDE4's device notifier, so you can just click & play a DVD in SMplayer. Awesome!
You need a very recent SMplayer and Mplayer, latter one compiled with dvdnav support.
- In SMplayer's preferences, go to mouse & keyboard -> mouse, and for left click select "Activate option in DVD menus".
- Create a file called smplayer-playdvd-predicate.desktop
in $KDEDIR/share/apps/solid/actions, here that means /usr/kde/svn/share/apps/solid/actions/smplayer-playdvd-predicate.desktop, with following in it:
[Desktop Entry] X-KDE-Solid-Predicate=[ StorageVolume.ignored == false AND OpticalDisc.availableContent == 'Data|VideoDvd' ] Type=Service Actions=open; [Desktop Action open] Name=Play DVD with SMplayer Exec=smplayer dvdnav:////%d Icon=smplayer
Now restart KDE, insert a DVD in your drive, or load DVD ISO image in cdemu, wait for the device notifier to pop up, and select.