Comment # 4 on bug 1219543 from Stefan Hundhammer

On TW, when you start

  sudo yast2 online_update

you will not get the YaST Online Update module, you will get the "sw_single"
module instead, where you can switch to the "Repositories" view, select the
"@System" category (all installed packages) from the list on the left. All the
packages with a blue version number have updated versions available, so you can
use menu "Package" -> "All in this list" -> "Update if newer version
available".

That is the very complicated counterpart to a 

  sudo zypper up

command line; notice that this does less than the recommended

  sudo zypper dup