### 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.
canceled = true;
}
void ProgressDialog::_bind_methods() {
}
ProgressDialog::ProgressDialog() {
	main = memnew(VBoxContainer);
	add_child(main);
	main->set_anchors_and_offsets_preset(Control::PRESET_FULL_RECT);
	set_exclusive(true);
	set_flag(Window::FLAG_POPUP, false);
	last_progress_tick = 0;
	singleton = this;
	cancel_hb = memnew(HBoxContainer);
	main->add_child(cancel_hb);
	cancel_hb->hide();
	cancel = memnew(Button);
	cancel_hb->add_spacer();
	cancel_hb->add_child(cancel);
	cancel->set_text(TTR("Cancel"));
	cancel_hb->add_spacer();
	cancel->connect("pressed", callable_mp(this, &ProgressDialog::_cancel_pressed));
}