### Godot version

v4.1.1.stable.official [bd6af8e0e]

### System information

Godot v4.1.1.stable - Debian GNU/Linux trixie/sid trixie - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (nvidia) - Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz (6 Threads)

### Issue description

`Area2D`s which extend beyond the bounds of the root viewport, eg. when using a `canvas_items` stretch mode, receive mouse input events even in the black bands letterboxing the game:

https://github.com/godotengine/godot/assets/441188/3beb962f-c1fa-4098-a375-f3d862013577


### Steps to reproduce

1. Set project stretch mode to either `canvas_items` or `viewport`
2. Have an `Area2D` whose `CollisionShape` extends beyond the bounds of the rendered region
3. Connect the `Area2D`'s `mouse_[entered|exited]` signal to something
4. Wave the mouse around in the black areas outside the rendered game

### Minimal reproduction project

Project used for video demo above:

[area2d-oob.zip](https://github.com/godotengine/godot/files/12207031/area2d-oob.zip)

This only demos `mouse_[entered|exited]`, but I first encountered this with the `Area2D.input_event` signal, where it received mouse clicks as well.
if (gui.sub_windows.size() < 2) {
		return;
	}
	if (!gui.sub_windows[gui.sub_windows.size() - 1].window->get_flag(Window::FLAG_ALWAYS_ON_TOP)) {
		int index = gui.sub_windows.size() - 1;
		while (index > 0 && gui.sub_windows[index - 1].window->get_flag(Window::FLAG_ALWAYS_ON_TOP)) {
			--index;
		}
		if (index != (gui.sub_windows.size() - 1)) {
			SubWindow sw = gui.sub_windows[gui.sub_windows.size() - 1];
			gui.sub_windows.remove_at(gui.sub_windows.size() - 1);
			gui.sub_windows.insert(index, sw);
		}
	}
	for (int i = 0; i < gui.sub_windows.size(); i++) {
		RS::get_singleton()->canvas_item_set_draw_index(gui.sub_windows[i].canvas_item, i);
	}
}
void Viewport::_sub_window_register(Window *p_window) {