This was found while working on JDK-8175358 as a review comment in PR - https://github.com/openjdk/jfx/pull/199.

It can be easily reproduced by either modifying test JDK-8175358 in to use a ContextMenu or running following JunitTest (to be added in AcceleratorParameterizedTest.java)

@Test public void testAcceleratorIsNotFiredWhenMenuItemRemovedFromScene() {
        KeyEventFirer kb = new KeyEventFirer(item1, scene);

        kb.doKeyPress(KeyCode.DIGIT1, KeyModifier.ALT);
        assertEquals(1, eventCounter);

        // Remove all children from the scene
        Group root = (Group)scene.getRoot();
        root.getChildren().clear();

        kb.doKeyPress(KeyCode.DIGIT1, KeyModifier.ALT);
        assertEquals(1, eventCounter);
    }