聊天频道：页签切换与频道屏蔽

-- 错误：切页签时清掉其它频道，切回全丢
function switchTab(tab)
    clearAll()
    showOnly(tab)
end

local cache = {world = {}, team = {}, sys = {}}
local curTab = "world"
local function pushMsg(tab, text)
    table.insert(cache[tab], text)
    if tab == curTab then
        appendLine(text)
    end
end
local function switchTab(tab)
    curTab = tab
    clearLines()
    for _, t in ipairs(cache[tab]) do
        appendLine(t)
    end
end