[bongo-patches] Prevent extra bongo-invisibility-padding

[Daniel Jensen]

The bongo-invisibility-padding hack did not check to see if there is
already padding present. This lead to extra space characters hanging
around. To see the results of the bug, collapse and then expand a top
level section containing a collapsed subsection.

--- bongo-old/bongo.el  2007-03-07 13:32:12.000000000 +0100
+++ bongo-new/bongo.el  2007-03-09 18:32:57.000000000 +0100
@@ -6875,8 +6875,9 @@
       ;; block of text starts with a character that does not
       ;; have a `display' property.  This character is later
       ;; removed by `bongo-expand'.
-      (insert (propertize " " 'invisible t
-                          'bongo-invisibility-padding t)))
+      (unless (get-text-property (point) 'bongo-invisibility-padding)
+        (insert (propertize " " 'invisible t
+                            'bongo-invisibility-padding t))))
     (let ((end (bongo-point-after-object)))
       (forward-line 1)
       (put-text-property (point) end 'invisible t)