[lgi/gtk] Hiding and then restoring a window ?

Hello,

I'm moving ahead with my application using lgi/gtk+ but I'm facing issue when I would like to hide and then restore a window. My code is the following :

---
window = Gtk.Window {
title = "Vigie v" .. Vigie_version,
icon_name = 'gnome-monitor',
window_position = Gtk.WindowPosition.MOUSE,
default_height = 150,
[blablabla my wingets here blablabla]
_on_destroy_ = function ()
window:hide()
end
}

statusicon = Gtk.StatusIcon {
visible = true,
tooltip_text = "I'm not sure",
_on_button_press_event_ = function ()
window:show_all()
end
}

Gtk.main() -- make it alive, waiting for events
---

So, at startup, my appl only add an icon in the system tray.
* When I click on this icon, the main window of my application is (correctly) displayed.
* when I click on the closing winget, the window disappears as expected
* but when click again on the systray icon, the window re-appears but without the geometry I requested and totally empty of child's winget.

So ... where I'm wrong ?

Thanks

Laurent