Linux Mint 13 ( Maya) is indeed a stable version but sometimes programs running on your system get frozen. That means, you unable to close the program using your mouse. Under that situation most of the Linux Mint users stuck helpless. Don’t worry this article will guide you through how to quit or close a program, if you encounter such situation.
To close any program, hit “Alt+F2″ from keyboard, type gnome-terminal and then hit ENTER. This will open the command terminal window.
Next, type the following command followed with your password:
sudo killall {application-name} For example, if you want to quit Firefox then type the command:
sudo killall firefox 
Well, that was about quitting a frozen program, what if you have multiple windows opened and you don’t know the application or program name?
To select the window that you wish to close with button, type the following command and use the cursor :
sudo xkill