Default parse format is changed for datepicker and calendar controls from "%Y-%m-%d" to "%Y-%m-%d %H:%i". Both of them can be altered within current locale.
Sizing of layouts changed. In Webix 2.2 and earlier height and width on layout were not including padding and margins. Starting from Webix 2.3 height and width of layout is a full size of layout, including all margings and paddings.
Check migration guide for more details.