### Godot version

4.0

### System information

Windows 11

### Issue description

When using a SubViewport contained within a SubviewportContainer, none of my child Control nodes within the Subviewport have their mouse cursors changed to align with their Control's default mouse cursor option. They are always unchanged, even when an attempt is made to change the default with code. It seems like being within a SubViewport disables it's ability to know when it needs to change mouse cursors inside that SubViewport.


### Steps to reproduce

* Create a Control node root.
* Put a SubViewportContainer inside it
* Put a SubViewport inside of that
* Put a ColorRect inside of the SubViewport and change it's default cursor to something else, such as "Forbidden"
* Hit "Play" and mouse over the ColorRect.

### Minimal reproduction project

[TestRepro.zip](https://github.com/godotengine/godot/files/10950080/TestRepro.zip)

ERR_FAIL_COND(p_event.is_null());
	Ref<InputEventMouseButton> mb = p_event;
	if (mb.is_valid()) {
		gui.key_event_accepted = false;
		Point2 mpos = mb->get_position();
		if (mb->is_pressed()) {
			if (!gui.mouse_focus_mask.is_empty()) {
				
				gui.mouse_focus_mask.set_flag(mouse_button_to_mask(mb->get_button_index()));
			} else {
				gui.mouse_focus = gui_find_control(mpos);
				gui.last_mouse_focus = gui.mouse_focus;
				if (!gui.mouse_focus) {
					return;
				}