Gunnar Evermann <ge204(a)eng.cam.ac.uk&gt; writes: If read the solution correctly it is another case of the problem where a function/code (possibly with side effects) given as an argument to the function is not executed at the right point (i.e. before the function call) when the compiler is optimizing (and presumably doing some inlining). If that is this the case then I remember seeing comments that XEmacs is working around these problems at other points in the code. If it is OK there, it is OK here. Jan