Index: /trunk/source/contrib/foy/source-comparison/source-compare-dialog.lisp
===================================================================
--- /trunk/source/contrib/foy/source-comparison/source-compare-dialog.lisp	(revision 12730)
+++ /trunk/source/contrib/foy/source-comparison/source-compare-dialog.lisp	(revision 12731)
@@ -231,8 +231,9 @@
                      ;; (#/isKeyWindow w)))))
          (window-pathname (w)
-           (let* ((pane (slot-value w 'gui::pane))
-                  (text-view (gui::text-pane-text-view pane))
-                  (buffer (gui::hemlock-buffer text-view)))
-             (hi::buffer-pathname buffer))))
+           (when w
+             (let* ((pane (slot-value w 'gui::pane))
+                    (text-view (gui::text-pane-text-view pane))
+                    (buffer (gui::hemlock-buffer text-view)))
+               (hi::buffer-pathname buffer)))))
 
     (list (make-button #@"Browse" 480 368 80 32
@@ -258,5 +259,5 @@
                            (declare (ignore item))
                            (let* ((window (front-hemlock-window))
-                                  (path (window-pathname window)))
+                                  (path (when window (window-pathname window))))
                              (when path 
                                (clear-difference-pane w)
@@ -268,5 +269,5 @@
                            (declare (ignore item))
                            (let* ((window (front-hemlock-window))
-                                  (path (window-pathname window)))
+                                  (path (when window (window-pathname window))))
                              (when path 
                                (clear-difference-pane w)