OK, but: As a (Mac) OS X developer, in 2003 I implemented a custom NSTextView subclass to fix two specific bugs that were impossible to work around otherwise. That subclass was used in everything we shipped for years and years... on OS X 10.3, 10.4, 10.5, 10.6, and 10.7.<p>(After that I lost track, but I think one or both bugs were finally fixed.)<p>I feel like maybe this change will make Apple frameworks more stable in the long run, but that will take a tech eternity (10+ years).<p>In the meantime, the overall user experience will be degraded by system framework bugs that can no longer be worked around. It just sounds more aspirational than realistic.<p>&quot;Let&#x27;s make it impossible for developers to work around our bugs -- that will <i>force</i> us to write perfect software!&quot;