(add-hook 'window-configuration-change-hook
	  (lambda ()
	    (setq frame-title-format
		  (concat
		   invocation-name "@" system-name ": "
		   (replace-regexp-in-string
		    (concat "/home/" user-login-name) "~"
		    (or buffer-file-name "%b"))))))

http://coldpeer.jogger.pl/2007/12/01/emacs-konfiguracja-belki-z-tytulem/

By default, Emacs displays on the titlebar (I mean GUI Emacs) emacs@domain. There is a way to modify this, using (setq frame-title-format "my title").

How to display emacs@domain: ~/dir/file (or buffer name in case of e.i. *scratch*)? Add it to your .emacs:

Titlebar customization, file name displaying

file

Emacs Lisp