[Pharo-dev] Spec row height for list of custom widgets

I'm trying to adapt this example from the Spec booklet... ListPresenter new displayBlock: [ :x | x buildWithSpec ]; items: ('Files' asPackage classes collect: [:cls | ButtonPresenter new icon: cls systemIcon; label: cls name]); openWithSpec to use my own presenter rather than ButtonPresenter, but it seems to be only showing the first line of my presenter. How can the height of each list row be changed. i.e. for the able sample code, how to make the buttons taller? cheers -ben