advanced menu function

local function newmenu(tList,x,y,height)
    local function maxlen(t)
        local len=0
        for i=1,#t do
            local curlen=string.len(type(t[i])=='table' and t[i][1] or t[i])
            if curlen>len then len=curlen end
        end
        return len
    end

    local max=maxlen(tList)
    x=x or 1
    y=y or 1
    y=y-1
    height=height or #tList
    height=height+1
    local selected=1
    local scrolled=0
    local function render()
        for num,item in ipairs(tList) do
            if num>scrolled and num<scrolled+height then
                term.setCursorPos(x,y+num-scrolled)
                local current=(type(item)=='table' and item[1] or item)
                write((num==selected and '[' or ' ')..current..(num==selected and ']' or ' ')..(max-#current>0 and string.rep(' ',max-#current) or ''))
            end
        end
    end
    while true do
        render()
        local evts={os.pullEvent('key')}
        if evts[1]=="key" and evts[2]==200 and selected>1 then
            if selected-1<=scrolled then scrolled=scrolled-1 end
            selected=selected-1
        elseif evts[1]=="key" and evts[2]==208 and selected<#tList then
            selected=selected+1
            if selected>=height+scrolled then scrolled=scrolled+1 end
        elseif evts[1]=="key" and evts[2]==28 or evts[2]==156 then
            return (type(tList[selected])=='table' and tList[selected][2](tList[selected][1]) or tList[selected])
        end
    end
end