FR: Support a horizontal ListBox

Obviously we can all copy the existing ListBox code and tweak it to suit these needs. It would just be better to have a solution provided already.

There are a few challenges, especially in API wording, that would cause breaking changes. For example: setRowHeight wouldn’t apply to a horizontal list box.

Looking back at this FR, it would be nice to collapse it as part of FRs: ListBox Improvements . My thinking is that horizontal support is easier to add into place after the generalised improvements.