kill-new discards current X selection

[Sam Steingold <sds@gnu.org>]

When I select a word in an xterm and then kill in emacs, then X selection is 
gone forever, replaced with the emacs kill.
The appended patch prepends the current X selection to kill-ring before 
replacing the X selection with the current Emacs kill.
Is it OK to install it unconditionally, or is it better to guard it with a user 
option, e.g., save-interprogram-paste-before-kill?


--- simple.el.~1.1005.~	2009-08-25 16:44:36.000000000 -0400
+++ simple.el	2009-08-26 12:15:19.000123000 -0400
@@ -2819,6 +2819,13 @@ argument should still be a \"useful\" st
  		(list string "yank-handler specified for empty string"))))
    (if (fboundp 'menu-bar-update-yank-menu)
        (menu-bar-update-yank-menu string (and replace (car kill-ring))))
+  (let ((interprogram-paste (and interprogram-paste-function
+				 (funcall interprogram-paste-function))))
+    (when interprogram-paste
+      (if (listp interprogram-paste)
+        (dolist (s (nreverse interprogram-paste))
+          (push s kill-ring))
+        (push interprogram-paste kill-ring))))
    (if (and replace kill-ring)
        (setcar kill-ring string)
      (push string kill-ring)