Fix MS-Windows tray notifications from different Emacs frames

* src/w32fns.c (EMACS_TRAY_NOTIFICATION_ID_INIT): Rename from
EMACS_TRAY_NOTIFICATION_ID; all users adjusted.
(last_tray_notification_id): New static variable.
(add_tray_notification): Advance 'last_tray_notification_id' for
each new notification; wrap around to the fixed initial value when
reached the maximum.  This allows Lisp programs track notifications
and remove them from the same frame from which they were created.
(Fw32_notification_notify, Fw32_notification_close): Doc fixes.

* doc/lispref/os.texi (Desktop Notifications): Update the
documentation of 'w32-notification-notify' and
'w32-notification-close'.

Bug#79400

1 files changed, 22 insertions, 10 deletions

diff --git a/src/w32fns.c b/src/w32fns.c
index 4aaafdd85d3..3fc0f55244f 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -10337,8 +10337,8 @@ typedef struct MY_NOTIFYICONDATAW {
 #endif
 
 
-#define EMACS_TRAY_NOTIFICATION_ID  42  /* arbitrary */
-#define EMACS_NOTIFICATION_MSG      (WM_APP + 1)
+#define EMACS_TRAY_NOTIFICATION_ID_INIT  42     /* arbitrary */
+#define EMACS_NOTIFICATION_MSG           (WM_APP + 1)
 
 enum NI_Severity {
   Ni_None,
@@ -10403,14 +10403,16 @@ utf8_mbslen_lim (const char *str, int lim)
   return mblen;
 }
 
+static unsigned short last_tray_notification_id;
+
 /* Low-level subroutine to show tray notifications.  All strings are
    supposed to be unibyte UTF-8 encoded by the caller.  */
-static EMACS_INT
+static int
 add_tray_notification (struct frame *f, const char *icon, const char *tip,
                        enum NI_Severity severity, unsigned timeout,
                        const char *title, const char *msg)
 {
-  EMACS_INT retval = EMACS_TRAY_NOTIFICATION_ID;
+  int retval = -1;
 
   if (FRAME_W32_P (f))
     {
@@ -10437,7 +10439,12 @@ add_tray_notification (struct frame *f, const char *icon, const char *tip,
       else
         nidw.cbSize = MYNOTIFYICONDATAW_V1_SIZE;                /* < W2K */
       nidw.hWnd = FRAME_W32_WINDOW (f);
-      nidw.uID = EMACS_TRAY_NOTIFICATION_ID;
+      if (!last_tray_notification_id)
+        last_tray_notification_id = EMACS_TRAY_NOTIFICATION_ID_INIT;
+      else
+        last_tray_notification_id++;
+      retval = last_tray_notification_id;
+      nidw.uID = last_tray_notification_id;
       nidw.uFlags = NIF_MESSAGE | NIF_ICON | NIF_TIP | NIF_INFO;
       nidw.uCallbackMessage = EMACS_NOTIFICATION_MSG;
       if (!*icon)
@@ -10660,16 +10667,19 @@ Note that versions of Windows before W2K support only `:icon' and `:tip'.
 You can pass the other parameters, but they will be ignored on
 those old systems.
 
-There can be at most one active notification at any given time.  An
-active notification must be removed by calling `w32-notification-close'
-before a new one can be shown.
+There can be at most one active notification at any given time per each
+Emacs frame.  An active notification must be removed by calling the
+function `w32-notification-close', with the same frame selected as the
+one which was selected when the notification was created, before a new
+one can be shown for the same frame.  The caller must track which
+notification was created from which frame, using the returned ID value.
 
 usage: (w32-notification-notify &rest PARAMS)  */)
   (ptrdiff_t nargs, Lisp_Object *args)
 {
   struct frame *f = SELECTED_FRAME ();
   Lisp_Object arg_plist, lres;
-  EMACS_INT retval;
+  int retval;
   char *icon, *tip, *title, *msg;
   enum NI_Severity severity;
   unsigned timeout = 0;
@@ -10732,7 +10742,9 @@ usage: (w32-notification-notify &rest PARAMS)  */)
 DEFUN ("w32-notification-close",
        Fw32_notification_close, Sw32_notification_close,
        1, 1, 0,
-       doc: /* Remove the MS-Windows tray notification specified by its ID.  */)
+       doc: /* Remove the MS-Windows tray notification specified by its ID.
+The frame which was selected when the notification was created must
+be selected when removing the notification.  */)
   (Lisp_Object id)
 {
   struct frame *f = SELECTED_FRAME ();