新手遮罩：首次进入的指引高亮

-- 错误：无指引满屏自由点，新手原地懵圈
function enterMain()
    showAllButtons()
end

local STEPS = {"questBtn", "bagBtn", "skillBtn"}
local function showStep(idx)
    local key = STEPS[idx]
    if key == nil then
        mask:setVisible(false)
        return
    end
    mask:setVisible(true)
    mask:highlight(panel:getChildByName(key))
end
local function onStepDone()
    saveGuideStep((readGuideStep() or 0) + 1)
    showStep(readGuideStep())
end