### 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.
Vector2 cpos(theme_cache.panel_style->get_offset());
	Vector2 csize(get_size() - theme_cache.panel_style->get_minimum_size());
	for (int i = 0; i < get_child_count(); i++) {
		Control *c = Object::cast_to<Control>(get_child(i));
		if (!c) {
			continue;
		}
		if (c->is_set_as_top_level()) {
			continue;
		}
		if (c == panel) {
			c->set_position(Vector2());
			c->set_size(get_size());
		} else {
			c->set_position(cpos);
			c->set_size(csize);
		}
	}
}
void PopupPanel::_update_theme_item_cache() {