   column do     panel "top on column 0"       # some code     end     panel "second on column 0"       # some code     end     panel "last on column 0"       # some code     end   end   column do     panel "top on column 0"       # some code     end     panel "second on column 0"       # some code     end     panel "last on column 0"       # some code     end   end 