[gimp] Doc NULL return for gimp_display_name() when no GUI.

[Ed J <edj src gnome org>]

commit df8964a1ce888770fe3dc080581eb53d166a3379
Author: Ed J <edj src gnome org>
Date:   Sat May 24 17:58:37 2014 +0100

    Doc NULL return for gimp_display_name() when no GUI.

 libgimp/gimp.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/libgimp/gimp.c b/libgimp/gimp.c
index e98819d..aea24b2 100644
--- a/libgimp/gimp.c
+++ b/libgimp/gimp.c
@@ -1341,6 +1341,8 @@ gimp_wm_class (void)
  * Returns the display to be used for plug-in windows.
  *
  * This is a constant value given at plug-in configuration time.
+ * Will return #NULL if GIMP has been started with no GUI, either
+ * via "--no-interface" flag, or a console build.
  *
  * Return value: the display name
  **/