quick frontends (widgets): added widgetNew and widgetDelete listeners:

- `widgetNew` is called when a brand new widget is created (not when a new instance is
  created if there is already an existing one)
- `widgetDelete` is called when all instances of a widget (with a given widget_hash) have
  been deleted.

sat_frontends/quick_frontend/constants.py

@@ -99,13 +99,15 @@ class Const(constants.Const):
         "nick",
         "presence",
         "selected",
+        "notification",
+        "notificationsClear",
+        "widgetNew",
+        "widgetDeleted",
         "profilePlugged",
         "contactsFilled",
         "disconnect",
         "gotMenus",
         "menu",
-        "notification",
-        "notificationsClear",
         "progressFinished",
         "progressError",
     }

sat_frontends/quick_frontend/quick_app.py

@@ -560,8 +560,13 @@ class QuickApp(object):
                 args: (selected_widget,)
             - notification: called when a new notification is emited
                 args: (entity, notification_data, profile)
-            - notification_clear: called when notifications are cleared
+            - notificationsClear: called when notifications are cleared
                 args: (entity, type_, profile)
+            - widgetNew: a new QuickWidget has been created
+                args: (widget,)
+            - widgetDeleted: all instances of a widget with specific hash have been
+                deleted
+                args: (widget_deleted,)
             - menu: called when a menu item is added or removed
                 args: (type_, path, path_i18n, item) were values are:
                     type_: same as in [sat.core.sat_main.SAT.importMenu]

sat_frontends/quick_frontend/quick_widgets.py

@@ -231,9 +231,10 @@ class QuickWidgetsManager(object):
 
         if widget is None:
             # we need to create a new widget
-            log.debug("Creating new widget for target {} {}".format(target, cls))
+            log.debug(f"Creating new widget for target {target} {cls}")
             widget = cls(*_args, **_kwargs)
             widgets_map.setdefault(hash_, []).append(widget)
+            self.host.callListeners("widgetNew", widget)
 
             if on_new_widget == C.WIDGET_NEW:
                 self.host.newWidget(widget)
@@ -341,6 +342,7 @@ class QuickWidgetsManager(object):
             del widgets_map[widget_hash]
             log.debug("All instances of {cls} with hash {widget_hash!r} have been deleted"
                 .format(cls=class_, widget_hash=widget_hash))
+            self.host.callListeners("widgetDeleted", widget_to_delete)
 
 
 class QuickWidget(object):