onDocumentCursorActive( event ) {

		this.showCursor();

		clearTimeout( this.cursorInactiveTimeout );

		this.cursorInactiveTimeout = setTimeout( this.hideCursor.bind( this ), this.Reveal.getConfig().hideCursorTime );

	}
Called whenever there is mouse input at the document level
to determine if the cursor is active or not.

@param {object} event