### Godot version

Godot Engine v4.0.stable.official.92bee43ad

### System information

Windows 10

### Issue description

The documentation states that passing ```null``` into the image parameter of ```set_custom_mouse_cursor``` will change it back to the system cursor, however I find that it removes the cursor's image entirely, rather than setting it to the system's cursor.


### Steps to reproduce

```var isimage = false
var theimage = load("res://final.png")

func _on_my_button_pressed():
    if isimage == false:
        Input.set_custom_mouse_cursor(theimage, Input.CURSOR_ARROW, Vector2(16,16))
        isimage = true
        
    else:
        Input.set_custom_mouse_cursor(null)
        isimage = false```

When the button is pressed, the cursor is meant to change to the new cursor. When it has been pressed a second time, it changes back to the default cursor. However, upon pressing it a second time, it simply disappears. The cursor becomes visible again when the cursor exits and re-enters the window.

### Minimal reproduction project

[null mouse.zip](https://github.com/godotengine/godot/files/10901969/null.mouse.zip)

return tablet_drivers.size();
}
String DisplayServerWindows::tablet_get_driver_name(int p_driver) const {
	if (p_driver < 0 || p_driver >= tablet_drivers.size()) {
		return "";
	} else {
		return tablet_drivers[p_driver];
	}
}
String DisplayServerWindows::tablet_get_current_driver() const {
	return tablet_driver;
}
void DisplayServerWindows::tablet_set_current_driver(const String &p_driver) {
	if (tablet_get_driver_count() == 0) {
		return;
	}
	bool found = false;
	for (int i = 0; i < tablet_get_driver_count(); i++) {
		if (p_driver == tablet_get_driver_name(i)) {
			found = true;
		}
	}
	if (found) {
		_update_tablet_ctx(tablet_driver, p_driver);
		tablet_driver = p_driver;
	} else {
		ERR_PRINT("Unknown tablet driver " + p_driver + ".");
	}
}
DisplayServerWindows::DisplayServerWindows(const String &p_rendering_driver, WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Vector2i *p_position, const Vector2i &p_resolution, int p_screen, Error &r_error) {