Back in 10.10, I was able to force close an application by clicking the force close icon on the panel on top. Now, with Unity, I am not able to add new icons on the panel. So is there like a keyboard shortcut to force close an application?
right click on desktop
name : xkill
command : xkill
double click to launch. drag to quicklaunch bar on left to launch from there...
you could even change the icon to the original icon by right click + properties, then click on the springboard icon picture which will take you to a browse window(choose an icon). Now navigate to the following folder /usr/share/icons/hicolor/scalable/apps and then find the icon named : gnome-panel-force-quit.svg, select it and voila.