+#if wxUSE_THREADS
+ // fork() doesn't mix well with POSIX threads: on many systems the program
+ // deadlocks or crashes for some reason. Probably our code is buggy and
+ // doesn't do something which must be done to allow this to work, but I
+ // don't know what yet, so for now just warn the user (this is the least we
+ // can do) about it
+ wxASSERT_MSG( wxThread::IsMain(),
+ _T("wxExecute() can be called only from the main thread") );
+#endif // wxUSE_THREADS
+