function Runes:UpdateUsable(frame, event, id, usable)
    if( not id ) then
        self:UpdateColors(frame)
        return
    elseif( not frame.runeBar.runes[id] ) then
        return
    end

    local rune = frame.runeBar.runes[id]
    local startTime, cooldown, cooled = GetRuneCooldown(id)
    if( not cooled and cooled ~= nil) then
        rune.endTime = startTime + cooldown
        rune:SetMinMaxValues(startTime, rune.endTime)
        rune:SetValue(GetTime())
        rune:SetAlpha(0.40)
        rune:SetScript("OnUpdate", runeMonitor)
    elseif (cooled == nil) then
        -- do nothing
    else
        rune:SetMinMaxValues(0, 1)
        rune:SetValue(1)
        rune:SetAlpha(1.0)
        rune:SetScript("OnUpdate", nil)
        rune.endTime = nil
    end

    if( rune.fontString ) then
        rune.fontString:UpdateTags()
    end
end