Determines visiblity of previous and next slides. A value of 100px will show 50px of previous and next slides. If value is set in percent for example 50{bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9} then 25{bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9} of previous slide will be visible, and 25{bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9} of next slide.