MutiColumn menu function

local function menu(opts,x1,y1,x2,y2,offset)
    local x,y=term.getSize()
    x1=x1 or 1
    y1=y1 or 1
    x2=x2 or x-1
    y2=y2 or y-1
    offset=offset or 1
    s=1
    sc=0

    local function maxlen(t)
        local len=0
        for num,ref in ipairs(opts) do
            local item=(type(ref)=='table' and ref[1] or ref)
            if len<#item then len=#item end
        end
        return len
    end

    local function render()
        local max=maxlen(opts)+2
        local columns=math.floor(x2/(max+offset))
        local curcol=0
        local line=0
        for num,ref in ipairs(opts) do
            curcol=(curcol+1>columns and (function() line=line+1 return 1 end)() or curcol+1)
            if line>=sc and y2+sc>=line+1 then
                term.setCursorPos(x1+(curcol-1)*(max+offset),y1+line-sc)
                local item=(type(ref)=='table' and ref[1] or ref)
                write((num==s and '[' or ' ')..item..(num==s and ']' or ' ')..(#item+2<max and string.rep(' ',max-#(item+2)) or ''))
            end
        end
        return columns
    end

    while true do
        local cols=render()
        local rows=math.ceil(s/cols)
        local evts={os.pullEvent()}
        if evts[1]=='key' and evts[2]==208 then
            s=(s+cols<=#opts and s+cols or #opts)
        elseif evts[1]=='key' and evts[2]==200 then
            s=(s-cols>=1 and s-cols or 1)
        elseif evts[1]=='key' and evts[2]==203 and s>1 then
            s=s-1
        elseif evts[1]=='key' and evts[2]==205 and s<#opts then
            s=s+1
        elseif evts[1]=='key' and evts[2]==28 then
            return (type(opts[s])=='table' and opts[s][2](opts[s][1]) or opts[s])
        end
        if math.ceil(s/cols)>sc+y2 then sc=math.ceil(s/cols)-y2 end
        if math.ceil(s/cols)<=sc then sc=math.ceil(s/cols)-1 end
    end
end

term.clear()
term.setCursorPos(1,1)
menu({'hello1','hello2','hello3','hello4','hello5','hello6'},2,2,20,2)