A solution for Jason Scharf's problem.

layout_test.rb

Shoes.app title: "asset manager", width: 1000 do
  flow do
    background rgb(191, 209, 229)
    stack do
      para "TOC Asset Manager", stroke: blue, font: "helvetica", align: "center", size: 20
    end

    stack width: 100 do
      caption "Encoders", font: "helvetica"
      %w[EBU41 EBU42 EBU43 EBU48 EBU49 EBU52 EBU53 EBU54 NET27 NET28 NET29 NET30 EBU91 EBU95].each do |name|
        flow do
          check
          flow(width: 70){para link(name, click: "http://192.168.1.1")}
        end
      end
    end

    stack( width: width-(100+200+20) ){}

    stack width: 200 do
      caption "Decoders", font: "helvetica"
      %w[EBU5 EBU6 EBU7 EBU8 EBU9 EBU10 EBU11 EBU12 EBU15 EBU16 EBU17 EBU18 EBU19 EBU20 EBU22 
         EBU23 EBU25 EBU26 EBU27 EBU28 EBU29 EBU30 EBU31 EBU32 EBU33 EBU40 EBU41 EBU42 EBU43
         EBU48 EBU49 EBU51 EBU52 EBU53 EBU55 EBU56 EBU57 EBU58 EBU59 EBU62 EBU63 EBU64 EBU65 EBU66].each do |name|
        flow do
          check
          flow(width: 70){para link(name, click: "http://192.168.1.1")}
          list_box items: ["NONE","TVRO1", "TVRO2", "TVRO3", "TVRO4", "TVRO5", "TVRO6", "ASI" ], width: 90, height: 20
        end
      end
    end
  end
end

This is a sample snippet to display the same layout on Red Shoes and Green Shoes.
A solution for Jason Scharf's problem.