[libgsystem] console: Further clarify escape codes

[Matthew Barnes <mbarnes src gnome org>]

commit 2ae5d113a29a2aa883f5597bf575dcd6c82141bc
Author: Matthew Barnes <mbarnes redhat com>
Date:   Wed Apr 15 13:08:02 2015 -0400

    console: Further clarify escape codes
    
    Found the flippin' manual.

 src/gsystem-console.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/gsystem-console.c b/src/gsystem-console.c
index 46b48af..806d619 100644
--- a/src/gsystem-console.c
+++ b/src/gsystem-console.c
@@ -346,9 +346,12 @@ gs_console_begin_status_line (GSConsole     *console,
 
   out = gs_console_get_stdout ();
 
+  /* This uses private DEC escape codes, defined at:
+   * http://vt100.net/docs/vt220-rm/chapter4.html#S4.7 */
+
   if (!console->in_status_line)
     {
-      /* See http://en.wikipedia.org/wiki/ANSI_escape_code, using the DEC codes */
+      /* Save Cursor (DECSC) - ESC 7 */
       guint8 buf[3] = { (guint8)'\n', 0x1B, 0x37 };
       if (!g_output_stream_write_all (out, buf, sizeof (buf), &bytes_written,
                                       cancellable, error))
@@ -358,6 +361,7 @@ gs_console_begin_status_line (GSConsole     *console,
     }
 
   {
+    /* Restore Cursor (DECRC) - ESC 8 */
     guint8 buf[2] = { 0x1B, 0x38 };
     if (!g_output_stream_write_all (out, buf, sizeof (buf), &bytes_written,
                                     cancellable, error))