menu-bar.el: x-selection-exists-p

[David Reitter <david.reitter@gmail.com>]

menu-bar.el contains two uses of `x-selection-exists-p', which is not  
defined if Emacs was built with "--without-x".

The first appears to disable the Paste menu item permanently; the  
second one calls the function even if it doesn't exist (even though  
I'm not sure if the `menu-enable' property on `clipboard-yank'  does  
what it appears to do).

Are the below  changes OK, and is it OK to check this in at this point?



Index: menu-bar.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/menu-bar.el,v
retrieving revision 1.350
diff -c -r1.350 menu-bar.el
*** menu-bar.el	14 Jan 2009 23:11:12 -0000	1.350
--- menu-bar.el	3 Mar 2009 04:11:59 -0000
***************
*** 459,466 ****
   	      :enable (and
   		       ;; Emacs compiled --without-x doesn't have
   		       ;; x-selection-exists-p.
! 		       (fboundp 'x-selection-exists-p)
! 		       (x-selection-exists-p) (not buffer-read-only))
   	      :help "Paste (yank) text most recently cut/copied"))
   (define-key menu-bar-edit-menu [copy]
     '(menu-item "Copy" menu-bar-kill-ring-save
--- 485,493 ----
   	      :enable (and
   		       ;; Emacs compiled --without-x doesn't have
   		       ;; x-selection-exists-p.
! 		       (if (fboundp 'x-selection-exists-p)
! 			   (x-selection-exists-p) t)
! 		       (not buffer-read-only))
   	      :help "Paste (yank) text most recently cut/copied"))
   (define-key menu-bar-edit-menu [copy]
     '(menu-item "Copy" menu-bar-kill-ring-save
***************
*** 495,503 ****
        '(and mark-active (not buffer-read-only)))
   (put 'clipboard-kill-ring-save 'menu-enable 'mark-active)
   (put 'clipboard-yank 'menu-enable
!      '(and (or (and (fboundp 'x-selection-exists-p)
! 		    (x-selection-exists-p))
! 	       (x-selection-exists-p 'CLIPBOARD))
   	   (not buffer-read-only)))

   (defun clipboard-yank ()
--- 527,535 ----
        '(and mark-active (not buffer-read-only)))
   (put 'clipboard-kill-ring-save 'menu-enable 'mark-active)
   (put 'clipboard-yank 'menu-enable
!      '(and (if (fboundp 'x-selection-exists-p)
! 	       (or (x-selection-exists-p)
! 		   (x-selection-exists-p 'CLIPBOARD)))
   	   (not buffer-read-only)))

   (defun clipboard-yank ()