Aded context menu to tabs widget; registered other widgets to registery

src/core/containers/header_container.py

@@ -37,6 +37,8 @@ class HeaderContainer(Gtk.Box):
         event_system.subscribe("tggl-top-main-menubar", self.tggl_top_main_menubar)
 
     def _load_widgets(self):
+        widget_registery.expose_object("header-container", self)
+
         button = Gtk.Button(label = "Interactive Debug")
         button.connect("clicked", self._interactive_debug)