There are assumptions that file io is sane, it's not. The file io we have will work just fine agaisnt local disk in most cases however all bets are off with network shares. SMB and NFS do not guarantee any instant response to even fflush/fsync/fclose. This means assumptions such as being able to immediately rename the temp file are wrong. wxWidgets also poorly handles wxTextFile which is a wxTempFile which is a wxFile which uses wxWrite which uses file descriptors instead of file objects that may trigger flushes too aggressively.