Review of attachment 294316 [details] [review]:

Some comments without looking at the real core of the patch

::: gedit/gedit-open-document-selector-store.c
@@ -111,3 +111,3 @@
 		}
 
-		item = (FileItem *)g_slice_new (FileItem);
+		item = (FileItem *)g_slice_new0 (FileItem);

I see that FileItem is allocated with g_slice_new in a few places. It is usually better to factor out create_file_item and free_file_item helpers

::: gedit/gedit-open-document-selector.c
@@ +111,3 @@
+}
+
+	while (*byte_array != BYTE_ARRAY_END && *byte_array == tag_found)

space before *

::: gedit/gedit-open-document-selector.h
@@ -42,2 +42,3 @@
 typedef struct _GeditOpenDocumentSelectorClassPrivate	GeditOpenDocumentSelectorClassPrivate;
 
+#define BYTE_ARRAY_END 0xFF

Does this need to be "public" in the .h? If no, let's move it to the .c file, if yes, it needs namespacing

@@ -42,2 +42,5 @@
 typedef struct _GeditOpenDocumentSelectorClassPrivate	GeditOpenDocumentSelectorClassPrivate;
 
+#define BYTE_ARRAY_END 0xFF
+
+/* Value 0xFF is reserved to mark the end of the array */

I guess this comment was for the define above and not for the enum?
If instead it is here because it is logically part of the enum note that you can do

enum
{
   A,
   B,
   C = 42
}

Also, at a quick glance it seems this could all go at the top of the .c file

Created attachment 294364 [details] [review]
open selector improvements

Created attachment 294367 [details] [review]
open selector improvements

commited as b34a069

The patch has been pushed, let's close the bug…