Introduced by RT-38884 (or not fully fixed): the change fired from selectedItems should contain _only_ the formerly selected items, not all items in the backing list.

    @Test
    public void testInvalidChange_38884() {
        getSelectionModel().select(3);
        int removedSize = getSelectionModel().getSelectedItems().size();
        ListChangeListener l = (Change c) -> {
            c.next();
            assertEquals(removedSize, c.getRemovedSize());
        };
        getSelectionModel().getSelectedItems().addListener(l);
        items.clear();
    }