[gnome-panel] doc: Add mention about per-screen settings

[Vincent Untz <vuntz src gnome org>]

commit 471e1530900cb7d8295a78a6c1c1973d72a7c10f
Author: Vincent Untz <vuntz gnome org>
Date:   Thu Feb 24 18:30:55 2011 +0100

    doc: Add mention about per-screen settings

 doc/reference/panel-applet/panel-applet-docs.sgml |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/doc/reference/panel-applet/panel-applet-docs.sgml b/doc/reference/panel-applet/panel-applet-docs.sgml
index 8c14146..cd96ee0 100644
--- a/doc/reference/panel-applet/panel-applet-docs.sgml
+++ b/doc/reference/panel-applet/panel-applet-docs.sgml
@@ -426,6 +426,10 @@ PANEL_APPLET_OUT_PROCESS_FACTORY ("HelloWorldFactory",
      </listitem>
     </itemizedlist>
 
+    <para>
+     There is actually a third case, which is rather rare, though: per-screen settings. It might be that some applets control some per-screen settings, like the layout of the workspaces. There is currently no API to help with this as it is a very specific case that you will probably never have to deal with for a usual applet.
+    </para>
+
      TODO: describe settings-oriented API
    </chapter>