### 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)

ERR_PRINT("invalid utf16 surrogate input");
							break; 
						}
						unicode = (prev_wck << 10UL) + unicode - ((0xd800 << 10UL) + 0xdc00 - 0x10000);
						prev_wck = 0;
					} else {
						prev_wck = 0;
					}
					k->set_unicode(fix_unicode(unicode));
				}
				if (k->get_unicode() && gr_mem) {
					k->set_alt_pressed(false);
					k->set_ctrl_pressed(false);
				}
				k->set_echo((ke.uMsg == WM_KEYDOWN && (ke.lParam & (1 << 30))));
				Input::get_singleton()->parse_input_event(k);
			} break;
		}
	}
	key_event_pos = 0;
}
void DisplayServerWindows::_update_tablet_ctx(const String &p_old_driver, const String &p_new_driver) {
	for (KeyValue<WindowID, WindowData> &E : windows) {
		WindowData &wd = E.value;
		wd.block_mm = false;
		if ((p_old_driver == "wintab") && wintab_available && wd.wtctx) {
			wintab_WTEnable(wd.wtctx, false);
			wintab_WTClose(wd.wtctx);
			wd.wtctx = 0;
		}