* Ask whether to wipe a session log file before writing to it.
* Returns 2 for wipe, 1 for append, 0 for cancel (don't log).
*/
-int askappend(void *frontend, Filename filename)
+int askappend(void *frontend, Filename filename,
+ void (*callback)(void *ctx, int result), void *ctx)
{
HANDLE hin;
DWORD savemode, i;