Change in the way item renderers lay them selves out. Before we were using 100% width and 100% height. Now, we're using horizontalAlign and verticalAlign to accomplish this, which are properties added to VerticalLayout and HorizontalLayout, respectively. horizontalAlign takes values "left", "center", "right", "justify", and "contentJustify". "justify" sizes all elements to the width of the component. "contentJustify" sizes all elements to the size of the largest child (with a minimum of the width of the parent component). Similar, verticalAlign takes "top", "middle", "bottom", "justify", and "contentJustify".
The default List skin sets the VerticalLayout's horizontalAlign to "contentJustify." Most lists should use "contentJustify" or "justify" if you don't want scrollbars. If you want to change your list to a horizontal list, you change the layout to a horizontal layout. However, you must set the verticalAlign property on the horizontal layout correctly--otherwise it'll default to "top" and probably won't do what you want.
Ran checkintests and the following mustella tests: layout, list, Group, DataGroup, FxDataContainer, and FxContainer. Some DataGroup tests were failing but should be because of an unrelated, local change. All other tests are passing.
QE Notes: Failing tests are excluded. Please update them (I think all just need to add verticalAlign="contentJustify" in the horizontal layout case) and re-include them. Also, please write tests for this new functionality.
Doc Notes: None