Why css hacks not patched by agent developers?

Question

Second line of the following is not recognisable by IE6/Windows

#header {margin-bottom:3em}
html>body #header {margin-bottom:1em}

I can understand that child selector is a feature not implemented by IE6. But IE/Mac will not recognize following.

/* Hide from IE-Mac \*/
#header {margin-bottom:3em}
#footer {margin-top:1.5em}
/* End hide */

This seems to be a bug. Usually agent developers gives patches. Why it is not patched? any specific reason?

Forgive me if it is too childish question.

Answer 1

Possible explanations:

1. In order not to break the existing hacks on hundreds of sites around
2. Too busy patching other hundreds bugs

Answer 2

Microsoft officially end-of-life'd Mac IE in 2003, so it doesn't get any updates or fixes.

(Given that it hasn't been updated in six years and has negligible use, there's really no reason to support it when designing pages.)

Answer 3

Rendering engines aren't typically patched. Browser patches are usually for security fixes, while rendering engine updates are rolled into major releases.

This is "helpful" inasmuch as you can rely on a browser's version number to exhibit the same behavior across all computers, so browser sniffers (frequently-broken as they may be) can target different versions as appropriate. It'd be nice if IE6 could be patched to render like IE8, you could never expect the patches to have very high market penetration, since so few people on older computers have automatic updates enabled.