https://bugzilla.xfce.org/show_bug.cgi?id=10760
解决方法
Every few weeks the tab key stops working in the terminal (no bash completion). Clearing "Settings > Window manager > Keyboard > Switch window for same application" fixes the problem
xfce terminal tab被解释为super+tab的bug
原文：http://www.cnblogs.com/rickerliang/p/5720641.html