How to hide "Navigation Toolbar" in Firefox 29?

You can install an addon or you can always add some CSS to your userchrome.css file which will allow you to hide the navigation bar like so:

• nav-bar, #urlbar-container, #search-container, #openLocation { display:none!important; }

Using FX29 with vimperator, I added following js code in .vimperatorrc (maybe _vimperatorrc on windows) to show and hide the navigation bar by F2 key.

map <silent> <F2> :js toggle_navbar()<CR>
:js << EOF
function toggle_navbar() {
    var nb = document.getElementById('nav-bar');
    if (!nb)
        return;
    nb.style.visibility = (nb.style.visibility == '') ? 'collapse' : '';
    nb.style.overflow = (nb.style.height == '') ? '' : 'hidden';
    }
toggle_navbar();
EOF

I didn't test this without vimperator, however, I hope some add-ons like "Execute JS" or so can help your trial.