[feature] Add and show the transient hint on notifications

ignis/services/notifications/notification.py

@@ -23,6 +23,7 @@ def __init__(
         timeout: int,
         time: float,
         popup: bool,
+        transient: bool,
     ):
         super().__init__()
 
@@ -36,6 +37,7 @@ def __init__(
         self._time = time
         self._urgency = urgency
         self._popup = popup
+        self._transient = transient
         self._actions = [
             NotificationAction(
                 id=str(actions[i]),
@@ -137,6 +139,13 @@ def popup(self) -> bool:
         """
         return self._popup
 
+    @IgnisProperty
+    def transient(self) -> bool:
+        """
+        Whether the notification is transient (ignored in any notification center implementation).
+        """
+        return self._transient
+
     @IgnisProperty
     def json(self) -> dict:
         """

ignis/services/notifications/service.py

@@ -220,6 +220,7 @@ def __init_notification(
             timeout=options.notifications.popup_timeout if timeout == -1 else timeout,
             time=datetime.now().timestamp(),
             popup=not options.notifications.dnd,
+            transient=hints.get("transient", False),
         )
 
         if len(self.popups) >= options.notifications.max_popups_count: