Binary package hint: network-manager-kde
This happened to both my installs of Kubuntu Karmic a5 with the identical results. Using the KDE applet I`m trying to add the connection.
Clicking "Managing connections" and naming the connection... Although there`s an "Auto eth0" connection there in applet, the list is initially empty. Entering my IP and gateway and DNS, but no way to enter netmask because there`s no such a field (?). After Ok and Apply, the connection (say, "Inet") cannot be activated from applet when clicking, no activity can be seen. "Auto eth0" works and tries to get an IP, which fails, of course.
Another thing is "Enable wireless" setting in applet, which cannot be set disabled permanently - it comes back after restart.
I can get network working only with editing config files as usual. Ths makes this applet totally unusable for me.
PS
Tried the Gnome applet in Karmic, and it works ok. BTW, netmask setting is there...
That`s not a pasma widget who does it, but a KDE Network Manager. However, after last updates I see the connection editor window changed and has everything to set it up. Now the problem is of another kind: my connection fails to start up automatically although requested to do so with a checkbox. And it (plasma widget at least) keeps showing "Enable wireless" checked on each startup? but even don`t have any wireless adapter.