990eb92bd9
When a `PanelMenu.Button` is added to the `statusArea`, its menu is added to the `PopupMenuManager` if it has one at the time. If a menu is added later or a new one set, the new menu is never added. Move the call to `PopupMenuManager.addMenu()` from `_addToPanelBox()` to `_onMenuSet()`, which is called when the `PanelMenu.Button` is added and whenever it emits the `menu-set` signal. Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2470>