Just for the record - keepalive_disable is set to msie6 and safari by default, but using the keepalive_disable directive explicitly disables keepalive for the specified arguments and implicitly enables (by not disabling) keepalive for all the other possible arguments.

So to enable keepalive for a browser that has keepalive disabled by default (which currently includes msie6 and safari) you have to use "keepalive_disable ID;", where ID is anything but the ID of the browser you want to enable keepalive for.

This disables keepalive for msie6 and implicitly enables keepalive for safari and all the other browsers:

keepalive_disable msie6;

This disables keepalive for safari and implicitly enables keepalive for msie6 and all the other browsers:

keepalive_disable safari;

This disables keepalive for safari and browser "none", and implicitly enables keepalive for msie6, but not due to the "none" argument:

keepalive_disable none safari;

That's because "none" does not actually reset the keepalive_disable variable to zero, it's implemented as another browser (2nd bit in the keepalive_disable browser bitmap), so specifying "none" as a single argument disables keepalive only for browser "none" and implicitly enables it for all the other browsers.

I know this directive is a workaround in the first place, but it would be nice if this were documented in the official documentation.