[evolution] Do not call gtk_main_quit() on shell quit when none is running

[Milan Crha <mcrha src gnome org>]

commit 0a016671ee2b5004df4fd2bca80f0e34e68476c3
Author: Milan Crha <mcrha redhat com>
Date:   Fri Jan 6 09:37:27 2012 +0100

    Do not call gtk_main_quit() on shell quit when none is running

 shell/e-shell.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/shell/e-shell.c b/shell/e-shell.c
index 32c43ff..dd0f4db 100644
--- a/shell/e-shell.c
+++ b/shell/e-shell.c
@@ -413,7 +413,8 @@ shell_ready_for_quit (EShell *shell,
 	g_list_foreach (list, (GFunc) gtk_widget_destroy, NULL);
 	g_list_free (list);
 
-	gtk_main_quit ();
+	if (gtk_main_level () > 0)
+		gtk_main_quit ();
 }
 
 static void