(tooltip-mode): Signal an error if x-show-tip

isn't fboundp.

diff --git a/lisp/tooltip.el b/lisp/tooltip.el
index dada23d0c2eb46b8fe267e0123344aa2fba990c1..e02eec718846b489a0fe98ba223f460898db6228 100644 (file)
--- a/lisp/tooltip.el
+++ b/lisp/tooltip.el
@@ -197,6 +197,8 @@ This might return nil if the event did not occur over a buffer."
   "Mode for tooltip display.
 With ARG, turn tooltip mode on if and only if ARG is positive."
   (interactive "P")
+  (unless (fboundp 'x-show-tip)
+    (error "Sorry, tooltips are not yet available on this system"))
   (let* ((on (if arg
                 (> (prefix-numeric-value arg) 0)
               (not tooltip-mode)))