What version of pike are you using? I think there may have been a bug in function where I didn't increment some list pointer in the get_children() function. You may have the buggy one still. You might have to get the latest cvs version. My code is latest cvs as of a few days ago. Per the log for gtkcontainer.pre (where the bug exists) it was fixed in 7.8.396, so you definitely have the buggy version. You should update to the latest cvs version:
http://pike.ida.liu.se/generated/pikefarm/packages/7.8/latest
Just wondering: Stable releases are announced quite rarely and 7.8.352 from September 2009 is still the one presented as the current stable on http://pike.ida.liu.se/. But since the 7.8 branch is a stable bramch, shouldn't all 7.8 versions be stable? Could you have made more officially stable releases?