I was looking exactly for the same thing, and found this wonderful script: http://askubuntu.com/a/280713/81372 http://askubuntu.com/a/280713/81372 I put it in

I was looking exactly for the same thing, and found this wonderful script: http://askubuntu.com/a/280713/81372 http://askubuntu.com/a/280713/81372 I put it in a custom keyboard shortcut, so I just press it, draw an onscreen rectangle around any non-selectable text, and in a few seconds it goes to the clipboard.