First of all, sorry for my English.
I'm trying to add an icon in the gnome-shell's dock (with Ubuntu 13.04 and 13.10) for the command line app
xkill, but it doesn't work, since it is a terminal application. But if I create the menu entry as a "terminal application" (writting it in a .desktop file or throghout the "Main Menu" application), it opens, consequently, a terminal with the message: "Select the window bla bla bla....".
What I really want is a more natural and direct way for closing a blocked window by force, and not by means of a terminal.
For older versions of gnome-shell there was a little extension which made it (adding a little icon in the top bar), but it exists no longer (or I haven't found it).