I think this patch could be useful for anyone who wants to drive an RS232 to RS485 converter in a Win32 environment.
It solves the problem of setting and resetting the RTS signal at the right time.
Please note that this doesn't work on Win95, Win98SE and WinME, as indicated here: http://support.microsoft.com/kb/140030.
I have added the parameter rtsToggle.
Setting rtsToggle to True and rtscts to False, the RTS signal goes high before the transmission starts and it goes low after the last byte has been transmitted.
If rtscts is set to True, the rtsToggle setting will be overridden.