function showHelp() {

		if( config.help ) {

			closeOverlay();

			dom.overlay = document.createElement( 'div' );
			dom.overlay.classList.add( 'overlay' );
			dom.overlay.classList.add( 'overlay-help' );
			dom.wrapper.appendChild( dom.overlay );

			var html = '<p class="title">Keyboard Shortcuts</p><br/>';

			html += '<table><th>KEY</th><th>ACTION</th>';
			for( var key in keyboardShortcuts ) {
				html += '<tr><td>' + key + '</td><td>' + keyboardShortcuts[ key ] + '</td></tr>';
			}

			html += '</table>';

			dom.overlay.innerHTML = [
				'<header>',
					'<a class="close" href="#"><span class="icon"></span></a>',
				'</header>',
				'<div class="viewport">',
					'<div class="viewport-inner">'+ html +'</div>',
				'</div>'
			].join('');

			dom.overlay.querySelector( '.close' ).addEventListener( 'click', function( event ) {
				closeOverlay();
				event.preventDefault();
			}, false );

			setTimeout( function() {
				dom.overlay.classList.add( 'visible' );
			}, 1 );

		}

	}
Opens a overlay window with help material.