Using Debian testing, I was anxiously waiting for new kernel 3.16.2, because it would solve some problems with my graphic and network configuration.
So I installed it and could configure wifi, network manager and plasma-nm are installed, wifi worked but there was no wired connection, so I added it, kept the defaults.
Problem is that widget does not detect it as an available connection, so when I disconnect wireless I have nothing.
This laptop is practically stationary, I only have wireless as a backup in case I need to move it,
How can I have both connections, use wired most of the time, and switch to wireless when needed?
EDIT:
Please disregard, I decided to install wicd and uninstall plasma-nm, because wicd does exactly what I want, use wired as the default.
Thanks anyway.

For future reference, the reason this occurred was likely because NetworkManager was probably not managing the Ethernet device. This is dependent on the content of /etc/network/interfaces on Debian based systems.