Unity cropping external monitor: how do I fix it?

I I have a dual-screen setup with my laptop (1366x768) and an external monitor connected through HDMI (primary 1920x1080).

I don't know if this is cause by different aspect ratios (16:10 on laptop, 16:9 on external monitor) but Unity appears cropped approximately as shown in this picture:

If I use a lower resolution (1680x1050, 16:10) the desktop is correctly displayed, but those extra pixels could be handy.

So is this any limitation/bug on Unity? How can I make it display the desktop correctly at 1920x1080 pixels?

In case it could help, output of xrandr command.

See HDMI/VGA connection cuts borders of screen or creates blurry text (and also Edges of screen cut off in Ubuntu 12.04):

NOTE (Comment made by User James -
https://askubuntu.com/users/39762/james): For some Samsung LCD TVs.
Using the TV Remote Control go to Options -> Picture Options and set
the Picture Option to "Fit to Screen".

Hope this helps.