Confirming that the workaround from comment #52 works, making the Alt+key shortcuts ("mnemonics", if you must abuse the English language) work happily in Unity in Ubuntu 13.04.
To recap and update slightly, do this:
1. Completely remove LibreOffice: sudo apt-get purge libreoffice*
2. Go to www.libreoffice.org and download the correct .deb.tar.gz for your OS, either 32 or 64 bit.
3. Unzip the file.
4. Change to the DEBS directory in the unzipped archive: cd [name of newly-created directory]/DEBS
5. Install every one of the sebs as superuser: sudo dpkg -i *.deb
To test, at the prompt type libreoffice and press Tab. As of 10 November 2013, the above process installs a program called libreoffice4.1, but presumably the name will change with the version.
I can report that:
- unlike the standard LO, this one responds when you press Alt+F, Alt+E and so on;
- it also handles the defined shortcuts as expected, for example Ctrl+D is fill down (which it isn't in OpenOffice, unless you change it - I hated that!);
- unlike standard LO with the libreoffice-gtk package removed, this does allow the window to work properly (eg maximise, minimise, etc) and uses the proper Open dialog box and so on;
- unlike OpenOffice, this doesn't have the irritating display bug where every item you select from a dropdown or type in an edit field remains and the fields get steadily darker as they're used because, apparently, the function to clear the rectangle before updating it is broken -- this may be an NVIDIA issue, but it's irritating nonetheless and I'm glad it's gone.
- the menus aren't integrated with the Macintosh-like top bar of Unity, which I don't care about but YMMV.
Only downside appears to be the icons for the software, which look like a standard Windows 3.1-era "text file" icon. Meh, I can live with a little ugliness.