[gtk+] Improve the docs

[Matthias Clasen <matthiasc src gnome org>]

commit 4371f370bca4ccf8379a29c71e0d4da11f66b95d
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Nov 28 22:52:44 2017 -0500

    Improve the docs
    
    Document that gtk_application_is_inhibited can't
    be guaranteed to work.

 gtk/gtkapplication.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkapplication.c b/gtk/gtkapplication.c
index f7bd5b5..39a4963 100644
--- a/gtk/gtkapplication.c
+++ b/gtk/gtkapplication.c
@@ -1158,6 +1158,9 @@ gtk_application_uninhibit (GtkApplication *application,
  * Determines if any of the actions specified in @flags are
  * currently inhibited (possibly by another application).
  *
+ * Note that this information may not be available (for example
+ * when the application is running in a sandbox).
+ *
  * Returns: %TRUE if any of the actions specified in @flags are inhibited
  *
  * Since: 3.4