The invalidateLayout method is advertised as a way to ensure that a layout manager that caches data discards the data when the data may no longer be valid. However, validation in Swing is asynchronous: "Validation will occur after all currently pending events have been dispatched," which means that pending events could make multiple invalidating changes. However, the invalidateLayout method is called only if the component is not already invalid. So, between the first invalidation and the deferred validation, invalidateLayout will not be called again, but the layout manager may have been called to provide sizing information and cached data in doing so. That cached data will not be discarded.

The attached test program demonstrates the problem using a custom layout manager. The stale cached data (red) remains even after the frame is packed.

Bug JDK-6893839 demonstrates the problem using BoxLayout.