Related to another question, is there a way to send SIGTERM to the currently focused local GUI window application with a keyboard shortcut? Like clicking the [X] button in most WMs or Ctrl-c for the command line. Not like Alt-SysRq-e since it kills every application :)
From the comments and from the linked question, I suspect that you want something like
There is a question on askubuntu about killing the active application. There is another question with an answer showing how to create a custom keyboard shortcut. You can combine the two to get a single keyboard shortcut that kills the active application. Of course, the bit about creating a keyboard shortcut depends on your window manager.
Working solution: Assign a new shortcut (as described above) pointing to