Hide editor_spin_slider grabber when closing Editor's windows

Fixes: #38740
(cherry picked from commit 095167dcc3cdca6264eff740a946970d79bca7e8)

editor/editor_spin_slider.cpp

@@ -196,6 +196,7 @@ void EditorSpinSlider::_notification(int p_what) {
 			p_what == MainLoop::NOTIFICATION_WM_FOCUS_IN ||
 			p_what == NOTIFICATION_EXIT_TREE) {
 		if (grabbing_spinner) {
+			grabber->hide();
 			Input::get_singleton()->set_mouse_mode(Input::MOUSE_MODE_VISIBLE);
 			grabbing_spinner = false;
 			grabbing_spinner_attempt = false;