For kde4.2.3 use these repos
Index of /repositories/KDE:/42/openSUSE_11.1
Index of /repositories/KDE:/KDE4:/Community/openSUSE_11.1_KDE_42
As I use 11.0, I have taken the repos for that version.
I have started a KDE4 session: all was running, excepted the Sys Tray.
You mention QT45, IMO you should not be using it
I have updated to QT4.5: then the Sys Tray was functionning, but Yast2 was corrupted.
So I will abandon to use KDE4 with 11.0 and remain with KDE3, which is running correctly.
Thank you again for your help.