Hmm not so simple.If you add "/usr/lib64/GNUstep/Applications/WPrefs.app/WPrefs" or "/usr/lib64/GNUstep/Applications/WPrefs.app/WPrefs %s" to the middle command section of the DOCK and then restart WM the commands disappear and you are back to square one. However if you add "/usr/lib64/GNUstep/Applications/WPrefs.app/WPrefs" to the middle command of the DOCK and close the settings you can middle click on the DOCK you open WPrefs.app and get an icon which you can attach to the DOCK. This survives a WM restart but the commands on the DOCK still disappear. It is a bit cludgy but it gives you access to WPrefs. Whew good old WM still as quirky as ever.