### Godot version

4.1.dev (dc625bcbfc5b587ba8867481ee7a1f6a567c25d0)

### System information

Mageia 9, Linux

### Issue description

When importing a project in current `master`, the following error is raised for each asset that gets imported:
```
Attempting to parent and popup a dialog that already has a parent.
```

It seems to be raised once per asset, caused by the progress dialog.

CC @bruvzg

### Steps to reproduce

- Import a new project in Godot that contains importable assets, e.g. https://github.com/RPicster/godot4-demo-desert-light

### Minimal reproduction project

See above.
RenderingServer *rendering_server = RenderingServer::get_singleton();
	if (rendering_server) {
		max_size = rendering_server->get_maximum_viewport_size();
		max_size_used = max_size; 
	}
	theme_owner = memnew(ThemeOwner);
	RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::VIEWPORT_UPDATE_DISABLED);
}
Window::~Window() {
	memdelete(theme_owner);
	
	for (KeyValue<StringName, Ref<Texture2D>> &E : theme_icon_override) {
		E.value->disconnect("changed", callable_mp(this, &Window::_notify_theme_override_changed));
	}
	for (KeyValue<StringName, Ref<StyleBox>> &E : theme_style_override) {
		E.value->disconnect("changed", callable_mp(this, &Window::_notify_theme_override_changed));
	}
	for (KeyValue<StringName, Ref<Font>> &E : theme_font_override) {
		E.value->disconnect("changed", callable_mp(this, &Window::_notify_theme_override_changed));
	}
	
	theme_icon_override.clear();
	theme_style_override.clear();
	theme_font_override.clear();
	theme_font_size_override.clear();
	theme_color_override.clear();
	theme_constant_override.clear();
}