How to know if a given port is Half or Full Duplex from Gnome?

[Fernando Cassia]

How to know on a gigabit Eth0 if a given port is working in half
duplex, full duplex,and if it's fast ethernet or full ethernet, from
Gnome/Fedora?

If I hover over the ETH0 icon in the notification area of the Gnome
bar I only see "Wired connection 'System eth0' active". Is there any
way to make it display "Wired connection ' system eth- active (1000
Mbit, Fulll Duplex)" or @"Wired connection ' system eth- active (1000
Mbit, Half Duplex)"

Would come very handing while testing cables....

Thanks!!!
FC