--- slime-cvs-1.1364.el	2011-05-09 14:46:38.000000000 -0400
+++ slime-20110320-cvs.el	2011-05-09 15:28:43.000000000 -0400
@@ -4988,22 +4973,30 @@
                       #'slime-initialize-macroexpansion-buffer)))
 
 (defun slime-macroexpand-again ()
-  "Reperform the last macroexpansion."
-  (interactive)
-  (slime-eval-async slime-eval-macroexpand-expression 
-                    (slime-rcurry #'slime-initialize-macroexpansion-buffer
-                                  (current-buffer))))
+ "Reperform the last macroexpansion."
+ (interactive)
+ (slime-eval-async slime-eval-macroexpand-expression
+   (slime-rcurry #'slime-initialize-macroexpansion-buffer
+                 (slime-buffer-name :macroexpansion))))
 
 (defun slime-initialize-macroexpansion-buffer (expansion &optional buffer)
-  (pop-to-buffer (or buffer (slime-create-macroexpansion-buffer)))
-  (setq buffer-undo-list nil) ; Get rid of undo information from
-                              ; previous expansions.
-  (let ((inhibit-read-only t)
-        (buffer-undo-list t)) ; Make the initial insertion not be undoable.
-    (erase-buffer)
-    (insert expansion)
-    (goto-char (point-min))
-    (font-lock-fontify-buffer)))
+  (let ((expansion-buffer 
+         (or (and buffer (get-buffer-create buffer))
+             (slime-create-macroexpansion-buffer))))
+    (with-current-buffer expansion-buffer
+      (pop-to-buffer (current-buffer))
+      (let ((inhibit-read-only t))
+        (if (eq (current-buffer) (get-buffer (slime-buffer-name :macroexpansion)))
+            (progn
+              ;; Get rid of undo information from previous expansions.              
+              (setq buffer-undo-list nil) 
+              (erase-buffer)
+              (let ((buffer-undo-list t)) ; Make the initial insertion not be undoable.
+                (insert expansion)
+                (font-lock-fontify-buffer)))
+          (let ((point-now (point)))
+            (save-excursion (insert expansion)
+                            (font-lock-fontify-region (point-now) (point)))))))))
 
 (defun slime-create-macroexpansion-buffer ()
   (let ((name (slime-buffer-name :macroexpansion)))
@@ -5012,7 +5005,7 @@
       (slime-mode 1)
       (slime-macroexpansion-minor-mode 1)
       (setq font-lock-keywords-case-fold-search t)
-      (current-buffer))))
+      (get-buffer name))))
 
 (defun slime-eval-macroexpand-inplace (expander)
   "Substitute the sexp at point with its macroexpansion.

Diff finished.  Mon May  9 15:34:18 2011