public boolean isTimeInWindow(long timeMillis) {
        // [)
        return startInMs <= timeMillis && timeMillis < endInMs;
    }
@Test
    void testIsTimeInWindow() {
        Pane<?> pane = new Pane<>(10, System.currentTimeMillis(), new Object());
        assertTrue(pane.isTimeInWindow(System.currentTimeMillis()));
        assertFalse(pane.isTimeInWindow(System.currentTimeMillis() + 10));
    }