The Wlan0 interface suddenly disappeared from nm-applet.
It might be linked to an issue I had with a dbus update, that erased the /etc/dbus-1/system.d directory.
I reinstalled dbus and network-manager, expecting that all necessary files are back.
Now I have :
I don’t use nm-applet, but: have you tried deleting preexisting wireless interfaces in YaST>Network Devices>Network Settings (if any) and then Adding a wireless interface?
In that case, I guess that the wpa-supplicant file really made the difference. Or maybe the avahi one also.
By the way, if someone would be nice enough to post here his system.d directory content, it would allow me to check definitely that I did not forget any other service.