Improve and document the language-change event on MS-Windows.

 src/keyboard.c (kbd_buffer_get_event): Include the codepage and the
 language ID in the event parameters.
 src/w32term.c (w32_read_socket): Put the new keyboard codepage into
 event.code, not the obscure "character set ID".
 doc/lispref/commands.texi (Misc Events): Document the language-change event.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/w32term.c b/src/w32term.c
index 6a4b3ca4afb..4f4fa220a7b 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -4234,8 +4234,8 @@ w32_read_socket (struct terminal *terminal, int expected,
           /* Generate a language change event.  */
           f = x_window_to_frame (dpyinfo, msg.msg.hwnd);
 
-          /* lParam contains the input lang ID.  Use it to update our
-             record of the keyboard codepage.  */
+          /* lParam contains the input language ID in its low 16 bits.
+             Use it to update our record of the keyboard codepage.  */
           keyboard_codepage = codepage_for_locale ((LCID)(msg.msg.lParam
                                                           & 0xffff));
 
@@ -4243,7 +4243,7 @@ w32_read_socket (struct terminal *terminal, int expected,
             {
               inev.kind = LANGUAGE_CHANGE_EVENT;
               XSETFRAME (inev.frame_or_window, f);
-              inev.code = msg.msg.wParam;
+              inev.code = keyboard_codepage;
               inev.modifiers = msg.msg.lParam & 0xffff;
             }
           break;