Adds a length class name to SC.SegmentedView. Example, with 3 items, the class of the view will include sc-length-3, which can be used to set a 33.3% width on each item through CSS. This allows the segments to be sized to fit the width or height of the view without having to set width properties on each item (which can be unweildy if the items are records for instance). While there are more modern ways to evenly distribute elements through CSS, this simple approach will work for browsers all the way back to IE7.
This allows duplicate items to appear in a collection and still be selected independently. Previously, all collection view selection was done per object, which would mean the first instance of the object in the content was always selected. Instead, selection is done by index only so that the same object can appear many times and each be selected separately.