Bamboo Feed Reader

评分5星，满分5星

由 matastic 发表于 Dec. 21, 2017 · 永久链接

FireTray

评分4星，满分5星

由 matastic 发表于 July 31, 2015 · 永久链接

Try middle click, it restores it.
At least in Kubuntu 15.04 with ThunderBird 31.8

TargetAlert

评分4星，满分5星

由 matastic 发表于 Sept. 17, 2007 · 永久链接

decent extension...

also, check out 'link alert'
and choose yourself

peace out!