[sawfish] Minor tooltip improvement: Don't show tooltip for empty keymap.

[Christopher Bratusek <chrisb src gnome org>]

commit 0628dcbde62e6b29eaac32746a2dbed2065a0a14
Author: Teika kazura <teika lavabit com>
Date:   Tue Feb 1 14:21:50 2011 +0900

    Minor tooltip improvement: Don't show tooltip for empty keymap.
    
    Padding frame classes, which are used for tab, have empty keymap. Don't show their tooltip.

 lisp/sawfish/wm/ext/tooltips.jl |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/lisp/sawfish/wm/ext/tooltips.jl b/lisp/sawfish/wm/ext/tooltips.jl
index b223e1d..2d24e5d 100644
--- a/lisp/sawfish/wm/ext/tooltips.jl
+++ b/lisp/sawfish/wm/ext/tooltips.jl
@@ -193,11 +193,12 @@
 	  items)
       (when (symbolp keymap)
 	(setq keymap (symbol-value keymap)))
-      (map-keymap (lambda (cell)
-		    (setq items (cons (cons (event-name (cdr cell))
-					    (command-info (car cell))) items)))
-		  keymap)
-      (display-tooltip (tooltips-format (nreverse items)))))
+      (when (cdr keymap)
+	(map-keymap (lambda (cell)
+		      (setq items (cons (cons (event-name (cdr cell))
+					      (command-info (car cell))) items)))
+		    keymap)
+	(display-tooltip (tooltips-format (nreverse items))))))
 
   (define (tooltips-fp-enter win fp)
     (declare (unused win))