The dedicated Media Buttons on the Thinkpad T420 keyboard(volume up, down, and mute)don't work when a LibreOffice writer, calc, or impress document (and possibly other modules - I don't know) is selected. The adjacent mute-microphone button works, however. I am running Windows 7 SP1, 64 bit. Processor: Intel Core i5-2520M.
Thanks for the report, but we already have this.
*** This bug has been marked as a duplicate of bug 32664 ***