Hey this is just a little test but why does it not work?FILE *test;int var=123;BOOL callback (PPIXPOINT relative_point, FLAGS32 mouse_flags){ test = fopen ("sonstwat.dat", "w+"); fprintf (test, "%d", var); fclose (test); return FALSE;}Thanks for some help,Etienne :-wave

Good question, what is the problem actually? In principle everything is OK, my file write operations are almost identical (I use "at" for protocolling or "wt" for other purposes). If this is mouse callback, don't forget the "FSAPI" (BOOL FSAPI callback(...). And of course don't forget #include <stdio.h> somewhere before this. You should also be aware that all paths are relative to the FS main directory so "sonstwat.dat" should be there.