Hi

although /usr/bin/kdm (KDE 4) has precedence over /opt/kde3/bin/kdm (KDE 3)
in the usual PATH, the Xorg startup file for "xdm" has a hard-coded 
reference to /opt/kde3/bin/kdm

I've searched too long, but all my (re)installations seem to provide the same
behaviour, whatever the order (xorg - KDE3 - KDE4)

I've added a KDE3->KDE4 precedence in /etc/init.d/xdm, allowing to have 
both all KDE 3 and 4 rpm files simultaneously on my host (I'll upgrade 
KDE4 every day), but only one of kde3-kdm or kde4-kdm in order to choose 
which KDE I'll start. (for convenience, I use KDE3 and /test/ KDE4...)




diff  -p  /etc/init.d/xdm  /etc/init.d/xdm.new
*** /etc/init.d/xdm     Wed Oct  3 12:42:21 2007
--- /etc/init.d/xdm.new Thu Jan 24 18:27:02 2008
*************** RELOADSIGNAL="-HUP"
*** 81,86 ****
--- 81,88 ----
  
  case "${DISPLAYMANAGER##*/}" in
      kdm|kde|KDM|KDE)   DISPLAYMANAGER=/opt/kde3/bin/kdm
+                        # hmmm, kde4 is under /usr/bin ;-)
+                        if [ ! -r "$DISPLAYMANAGER" ]; then DISPLAYMANAGER=/usr/bin/kdm; fi
                         PIDFILE="/var/run/kdm.pid"
                         ;;
      xdm)               DISPLAYMANAGER=$XDM_BIN
*************** case "${DISPLAYMANAGER##*/}" in
*** 94,103 ****
      console)           exit 0
                         ;;
      *)                         DISPLAYMANAGER=$XDM_BIN
                         if test -x /opt/kde3/bin/kdm; then
                                DISPLAYMANAGER=/opt/kde3/bin/kdm
                                PIDFILE="/var/run/kdm.pid"
!                        fi 
                         ;;
  esac
  test ! -x "$DISPLAYMANAGER" && DISPLAYMANAGER=$XDM_BIN
--- 96,109 ----
      console)           exit 0
                         ;;
      *)                         DISPLAYMANAGER=$XDM_BIN
+                        # keep KDE3 precedence over KDE4
                         if test -x /opt/kde3/bin/kdm; then
                                DISPLAYMANAGER=/opt/kde3/bin/kdm
                                PIDFILE="/var/run/kdm.pid"
!                        elif test -x /usr/bin/kdm; then
!                               DISPLAYMANAGER=/usr/bin/kdm; fi
!                               PIDFILE="/var/run/kdm.pid"
!                        fi
                         ;;
  esac
  test ! -x "$DISPLAYMANAGER" && DISPLAYMANAGER=$XDM_BIN