The cause was that the replace code necessarily used a PCRE internal
function to to template expansion.
The fix changes the code to use an SRE internal if SRE is used, and a
PCRE internal if SRE is used; in a way that should work with 1.5.2.
The solution can be sped up tremendously under the assumption that the
choice between sre and pre is not changed during the execution of the
program; especially replace-all will be slow.
But I'll leave that to someone else.
Much has changed -- too much, in fact, to write down.
The big news is that there's a standard way to write IDLE extensions;
see extend.txt. Some sample extensions have been provided, and
some existing code has been converted to extensions. Probably the
biggest new user feature is a new search dialog with more options,
search and replace, and even search in files (grep).
This is exactly as downloaded from my laptop after returning
from the holidays -- it hasn't even been tested on Unix yet.
Guido van Rossum