Ubuntu 14.04，启用了Gnome经典模式(Fallback)。这种情况下，删除启动栏的图标一直是一个难题。
看了解决方案后，再次给Gnome/Ubuntu跪了。。这是什么奇葩设计思路。。
转载自：http://askubuntu.com/questions/91445/how-do-i-remove-an-icon-from-the-top-panel-in-gnome-fallback-mode
You are using the Gnome-Classic interface - either you are using this by choice, or you are using the fallback mode which occurs if your graphics card & driver doesnt the 3D Acceleration required for the full Gnome-Shell GUI.
To add and remove application launchers in the gnome-panel you need to:
Press Win+Alt and right-click the top menu bar - N.B. Win is the Windows Symbol key
If you are not using Compiz then you need to :
Press Alt and right-click the top menu bar
Much more information is described in the linked Q&A and other links in that answer.
一直用alt+right click，上次重新装了一遍，发现这个组合不好使了。ＭＤ原来默认安装了compiz得多加一个win键，果断把compiz卸载。