onDocumentKeyDown( event ) {

		let config = this.Reveal.getConfig();

		// If there's a condition specified and it returns false,
		// ignore this event
		if( typeof config.keyboardCondition === 'function' && config.keyboardCondition(event) === false ) {
			return true;
		}

		// If keyboardCondition is set, only capture keyboard events
		// for embedded decks when they are focused
		if( config.keyboardCondition === 'focused' && !this.Reveal.isFocused() ) {
			return true;
		}

		// Shorthand
		let keyCode = event.keyCode;

		// Remember if auto-sliding was paused so we can toggle it
		let autoSlideWasPaused = !this.Reveal.isAutoSliding();

		this.Reveal.onUserInput( event );

		// Is there a focused element that could be using the keyboard?
		let activeElementIsCE = document.activeElement && document.activeElement.isContentEditable === true;
		let activeElementIsInput = document.activeElement && document.activeElement.tagName && /input|textarea/i.test( document.activeElement.tagName );
		let activeElementIsNotes = document.activeElement && document.activeElement.className && /speaker-notes/i.test( document.activeElement.className);

		// Whitelist certain modifiers for slide navigation shortcuts
		let keyCodeUsesModifier = [32, 37, 38, 39, 40, 63, 78, 80, 191].indexOf( event.keyCode ) !== -1;

		// Prevent all other events when a modifier is pressed
		let unusedModifier = 	!( keyCodeUsesModifier && event.shiftKey || event.altKey ) &&
								( event.shiftKey || event.altKey || event.ctrlKey || event.metaKey );

		// Disregard the event if there's a focused element or a
		// keyboard modifier key is present
		if( activeElementIsCE || activeElementIsInput || activeElementIsNotes || unusedModifier ) return;

		// While paused only allow resume keyboard events; 'b', 'v', '.'
		let resumeKeyCodes = [66,86,190,191,112];
		let key;

		// Custom key bindings for togglePause should be able to resume
		if( typeof config.keyboard === 'object' ) {
			for( key in config.keyboard ) {
				if( config.keyboard[key] === 'togglePause' ) {
					resumeKeyCodes.push( parseInt( key, 10 ) );
				}
			}
		}

		if( this.Reveal.isOverlayOpen() && !["Escape", "f", "c", "b", "."].includes(event.key) ) {
			return false;
		}

		if( this.Reveal.isPaused() && resumeKeyCodes.indexOf( keyCode ) === -1 ) {
			return false;
		}

		// Use linear navigation if we're configured to OR if
		// the presentation is one-dimensional
		let useLinearMode = config.navigationMode === 'linear' || !this.Reveal.hasHorizontalSlides() || !this.Reveal.hasVerticalSlides();

		let triggered = false;

		// 1. User defined key bindings
		if( typeof config.keyboard === 'object' ) {

			for( key in config.keyboard ) {

				// Check if this binding matches the pressed key
				if( parseInt( key, 10 ) === keyCode ) {

					let value = config.keyboard[ key ];

					// Callback function
					if( typeof value === 'function' ) {
						value.apply( null, [ event ] );
					}
					// String shortcuts to reveal.js API
					else if( typeof value === 'string' && typeof this.Reveal[ value ] === 'function' ) {
						this.Reveal[ value ].call();
					}

					triggered = true;

				}

			}

		}

		// 2. Registered custom key bindings
		if( triggered === false ) {

			for( key in this.bindings ) {

				// Check if this binding matches the pressed key
				if( parseInt( key, 10 ) === keyCode ) {

					let action = this.bindings[ key ].callback;

					// Callback function
					if( typeof action === 'function' ) {
						action.apply( null, [ event ] );
					}
					// String shortcuts to reveal.js API
					else if( typeof action === 'string' && typeof this.Reveal[ action ] === 'function' ) {
						this.Reveal[ action ].call();
					}

					triggered = true;
				}
			}
		}

		// 3. System defined key bindings
		if( triggered === false ) {

			// Assume true and try to prove false
			triggered = true;

			// P, PAGE UP
			if( keyCode === 80 || keyCode === 33 ) {
				this.Reveal.prev({skipFragments: event.altKey});
			}
			// N, PAGE DOWN
			else if( keyCode === 78 || keyCode === 34 ) {
				this.Reveal.next({skipFragments: event.altKey});
			}
			// H, LEFT
			else if( keyCode === 72 || keyCode === 37 ) {
				if( event.shiftKey ) {
					this.Reveal.slide( 0 );
				}
				else if( !this.Reveal.overview.isActive() && useLinearMode ) {
					if( config.rtl ) {
						this.Reveal.next({skipFragments: event.altKey});
					}
					else {
						this.Reveal.prev({skipFragments: event.altKey});
					}
				}
				else {
					this.Reveal.left({skipFragments: event.altKey});
				}
			}
			// L, RIGHT
			else if( keyCode === 76 || keyCode === 39 ) {
				if( event.shiftKey ) {
					this.Reveal.slide( this.Reveal.getHorizontalSlides().length - 1 );
				}
				else if( !this.Reveal.overview.isActive() && useLinearMode ) {
					if( config.rtl ) {
						this.Reveal.prev({skipFragments: event.altKey});
					}
					else {
						this.Reveal.next({skipFragments: event.altKey});
					}
				}
				else {
					this.Reveal.right({skipFragments: event.altKey});
				}
			}
			// K, UP
			else if( keyCode === 75 || keyCode === 38 ) {
				if( event.shiftKey ) {
					this.Reveal.slide( undefined, 0 );
				}
				else if( !this.Reveal.overview.isActive() && useLinearMode ) {
					this.Reveal.prev({skipFragments: event.altKey});
				}
				else {
					this.Reveal.up({skipFragments: event.altKey});
				}
			}
			// J, DOWN
			else if( keyCode === 74 || keyCode === 40 ) {
				if( event.shiftKey ) {
					this.Reveal.slide( undefined, Number.MAX_VALUE );
				}
				else if( !this.Reveal.overview.isActive() && useLinearMode ) {
					this.Reveal.next({skipFragments: event.altKey});
				}
				else {
					this.Reveal.down({skipFragments: event.altKey});
				}
			}
			// HOME
			else if( keyCode === 36 ) {
				this.Reveal.slide( 0 );
			}
			// END
			else if( keyCode === 35 ) {
				this.Reveal.slide( this.Reveal.getHorizontalSlides().length - 1 );
			}
			// SPACE
			else if( keyCode === 32 ) {
				if( this.Reveal.overview.isActive() ) {
					this.Reveal.overview.deactivate();
				}
				if( event.shiftKey ) {
					this.Reveal.prev({skipFragments: event.altKey});
				}
				else {
					this.Reveal.next({skipFragments: event.altKey});
				}
			}
			// TWO-SPOT, SEMICOLON, B, V, PERIOD, LOGITECH PRESENTER TOOLS "BLACK SCREEN" BUTTON
			else if( [58, 59, 66, 86, 190].includes( keyCode ) || ( keyCode === 191 && !event.shiftKey ) ) {
				this.Reveal.togglePause();
			}
			// F
			else if( keyCode === 70 ) {
				enterFullscreen( config.embedded ? this.Reveal.getViewportElement() : document.documentElement );
			}
			// A
			else if( keyCode === 65 ) {
				if( config.autoSlideStoppable ) {
					this.Reveal.toggleAutoSlide( autoSlideWasPaused );
				}
			}
			// G
			else if( keyCode === 71 ) {
				if( config.jumpToSlide ) {
					this.Reveal.toggleJumpToSlide();
				}
			}
			// C
			else if( keyCode === 67 && this.Reveal.isOverlayOpen() ) {
				this.Reveal.closeOverlay();
			}
			// ?
			else if( ( keyCode === 63 || keyCode === 191 ) && event.shiftKey ) {
				this.Reveal.toggleHelp();
			}
			// F1
			else if( keyCode === 112 ) {
				this.Reveal.toggleHelp();
			}
			else {
				triggered = false;
			}

		}

		// If the input resulted in a triggered action we should prevent
		// the browsers default behavior
		if( triggered ) {
			event.preventDefault && event.preventDefault();
		}
		// ESC or O key
		else if( keyCode === 27 || keyCode === 79 ) {
			if( this.Reveal.closeOverlay() === false ) {
				this.Reveal.overview.toggle();
			}

			event.preventDefault && event.preventDefault();
		}
		
		// Enter to exit overview mode
		else if (keyCode === 13 && this.Reveal.overview.isActive()) {
			this.Reveal.overview.deactivate();
			event.preventDefault && event.preventDefault();
		}

		// If auto-sliding is enabled we need to cue up
		// another timeout
		this.Reveal.cueAutoSlide();

	}
Handler for the document level 'keydown' event.

@param {object} event