Index: thunar/thunar-file.c
===================================================================
--- thunar/thunar-file.c	(revision 21175)
+++ thunar/thunar-file.c	(working copy)
@@ -500,22 +500,37 @@
     {
       /* we're the owner, so the usr permissions must be granted */
       result = ((mode & usr_permissions) == 0);
+  
+      /* release the user */
+      g_object_unref (G_OBJECT (user));
     }
   else
     {
       group = thunar_file_get_group (file);
       if (G_LIKELY (group != NULL))
         {
-          /* check the group permissions */
-          groups = thunar_vfs_user_get_groups (user);
-          for (lp = groups; lp != NULL; lp = lp->next)
-            if (THUNAR_VFS_GROUP (lp->data) == group)
-              {
-                g_object_unref (G_OBJECT (user));
-                g_object_unref (G_OBJECT (group));
-                return ((mode & grp_permissions) == 0);
-              }
+          /* release the file owner */
+          g_object_unref (G_OBJECT (user));
 
+          /* determine the effective user */
+          user = thunar_vfs_user_manager_get_user_by_id (user_manager, effective_user_id);
+          if (G_LIKELY (user != NULL))
+            {
+              /* check the group permissions */
+              groups = thunar_vfs_user_get_groups (user);
+              for (lp = groups; lp != NULL; lp = lp->next)
+                if (THUNAR_VFS_GROUP (lp->data) == group)
+                  {
+                    g_object_unref (G_OBJECT (user));
+                    g_object_unref (G_OBJECT (group));
+                    return ((mode & grp_permissions) == 0);
+                  }
+          
+              /* release the effective user */
+              g_object_unref (G_OBJECT (user));
+            }
+
+          /* release the file group */
           g_object_unref (G_OBJECT (group));
         }
 
@@ -523,8 +538,6 @@
       result = ((mode & oth_permissions) == 0);
     }
 
-  g_object_unref (G_OBJECT (user));
-
   return result;
 }
 
@@ -1330,46 +1343,6 @@
 
 
 /**
- * thunar_file_is_executable:
- * @file : a #ThunarFile instance.
- *
- * Determines whether the owner of the current process is allowed
- * to execute the @file (or enter the directory refered to by
- * @file).
- *
- * Return value: %TRUE if @file can be executed.
- **/
-gboolean
-thunar_file_is_executable (const ThunarFile *file)
-{
-  g_return_val_if_fail (THUNAR_IS_FILE (file), FALSE);
-  return ((file->info->flags & THUNAR_VFS_FILE_FLAGS_EXECUTABLE) != 0);
-}
-
-
-
-/**
- * thunar_file_is_readable:
- * @file : a #ThunarFile instance.
- *
- * Determines whether the owner of the current process is allowed
- * to read the @file.
- *
- * Return value: %TRUE if @file can be read.
- **/
-gboolean
-thunar_file_is_readable (const ThunarFile *file)
-{
-  g_return_val_if_fail (THUNAR_IS_FILE (file), FALSE);
-  return !thunar_file_denies_access_permission (file,
-                                                THUNAR_VFS_FILE_MODE_USR_READ,
-                                                THUNAR_VFS_FILE_MODE_GRP_READ,
-                                                THUNAR_VFS_FILE_MODE_OTH_READ);
-}
-
-
-
-/**
  * thunar_file_is_renameable:
  * @file : a #ThunarFile instance.
  *
@@ -1405,29 +1378,6 @@
 
 
 /**
- * thunar_file_is_writable:
- * @file : a #ThunarFile instance.
- *
- * Determines whether the owner of the current process is allowed
- * to write the @file.
- *
- * Return value: %TRUE if @file can be read.
- **/
-gboolean
-thunar_file_is_writable (const ThunarFile *file)
-{
-  g_return_val_if_fail (THUNAR_IS_FILE (file), FALSE);
-  return !thunar_file_denies_access_permission (file,
-                                                THUNAR_VFS_FILE_MODE_USR_WRITE,
-                                                THUNAR_VFS_FILE_MODE_GRP_WRITE,
-                                                THUNAR_VFS_FILE_MODE_OTH_WRITE);
-
-
-}
-
-
-
-/**
  * thunar_file_get_actions:
  * @file   : a #ThunarFile instance.
  * @window : a #GdkWindow instance.
Index: thunar/thunar-file.h
===================================================================
--- thunar/thunar-file.h	(revision 21175)
+++ thunar/thunar-file.h	(working copy)
@@ -155,10 +155,7 @@
 ThunarVfsUser    *thunar_file_get_user             (const ThunarFile       *file);
 
 gboolean          thunar_file_is_chmodable         (const ThunarFile       *file);
-gboolean          thunar_file_is_executable        (const ThunarFile       *file);
-gboolean          thunar_file_is_readable          (const ThunarFile       *file);
 gboolean          thunar_file_is_renameable        (const ThunarFile       *file);
-gboolean          thunar_file_is_writable          (const ThunarFile       *file);
 
 GList            *thunar_file_get_actions          (ThunarFile             *file,
                                                     GtkWidget              *window);
@@ -359,6 +356,40 @@
 #define thunar_file_is_directory(file) (THUNAR_FILE ((file))->info->type == THUNAR_VFS_FILE_TYPE_DIRECTORY)
 
 /**
+ * thunar_file_is_executable:
+ * @file : a #ThunarFile instance.
+ *
+ * Determines whether the owner of the current process is allowed
+ * to execute the @file (or enter the directory refered to by
+ * @file).
+ *
+ * Return value: %TRUE if @file can be executed.
+ **/
+#define thunar_file_is_executable(file) (THUNAR_FILE ((file))->info->flags & THUNAR_VFS_FILE_FLAGS_EXECUTABLE)
+
+/**
+ * thunar_file_is_readable:
+ * @file : a #ThunarFile instance.
+ *
+ * Determines whether the owner of the current process is allowed
+ * to read the @file.
+ *
+ * Return value: %TRUE if @file can be read.
+ **/
+#define thunar_file_is_readable(file) (THUNAR_FILE ((file))->info->flags & THUNAR_VFS_FILE_FLAGS_READABLE)
+
+/**
+ * thunar_file_is_writable:
+ * @file : a #ThunarFile instance.
+ *
+ * Determines whether the owner of the current process is allowed
+ * to write the @file.
+ *
+ * Return value: %TRUE if @file can be read.
+ **/
+#define thunar_file_is_writable(file) (THUNAR_FILE ((file))->info->flags & THUNAR_VFS_FILE_FLAGS_WRITABLE)
+
+/**
  * thunar_file_is_hidden:
  * @file : a #ThunarFile instance.
  *
Index: thunar-vfs/thunar-vfs-types.h
===================================================================
--- thunar-vfs/thunar-vfs-types.h	(revision 21175)
+++ thunar-vfs/thunar-vfs-types.h	(working copy)
@@ -129,6 +129,10 @@
  *                                     hidden files. Hidden files start with a
  *                                     dot character ('.') or end with a tilde
  *                                     character ('~').
+ * @THUNAR_VFS_FILE_FLAGS_READABLE   : The file can most probably be read by the
+ *                                     current user.
+ * @THUNAR_VFS_FILE_FLAGS_WRITABLE   : The file can most probably be written by
+ *                                     the current user.
  *
  * Flags providing additional information about the
  * file system entity.
@@ -139,6 +143,8 @@
   THUNAR_VFS_FILE_FLAGS_SYMLINK    = 1L << 0,
   THUNAR_VFS_FILE_FLAGS_EXECUTABLE = 1L << 1,
   THUNAR_VFS_FILE_FLAGS_HIDDEN     = 1L << 2,
+  THUNAR_VFS_FILE_FLAGS_READABLE   = 1L << 3,
+  THUNAR_VFS_FILE_FLAGS_WRITABLE   = 1L << 4,
 } ThunarVfsFileFlags;
 
 typedef dev_t ThunarVfsFileDevice;
Index: thunar-vfs/thunar-vfs-info.c
===================================================================
--- thunar-vfs/thunar-vfs-info.c	(revision 21175)
+++ thunar-vfs/thunar-vfs-info.c	(working copy)
@@ -843,6 +843,14 @@
         }
     }
 
+  /* check if we can read the file */
+  if ((info->mode & 00444) != 0 && g_access (absolute_path, R_OK) == 0)
+    info->flags |= THUNAR_VFS_FILE_FLAGS_READABLE;
+
+  /* check if we can write to the file */
+  if ((info->mode & 00222) != 0 && g_access (absolute_path, W_OK) == 0)
+    info->flags |= THUNAR_VFS_FILE_FLAGS_WRITABLE;
+
   /* determine the file's mime type */
   switch (info->type)
     {