This is especially useful since on most Linux systems (not sure about other
OS'es), a serial-to-USB converter attached to a USB port appears as device
/dev/ttyUSB[0-...], for instance /dev/ttyUSB0.  The resulting device accepts
'standard' RS232 serial I/O, so all that is needed in order to support computers
with USB+converter is a change of device name from /dev/ttys0 to /dev/ttyUSB0
(in this example).

Created attachment 48078 [details] [review]
proposed patch

Remus, I don't understand this patch.  It seems to be a compile-time serial port
option, which isn't very useful for the problem stated.

I recommend making it possible for the end-user to specify a non-standard serial
port/device name at runtime, without requiring a command line argument.  There
are two approaches that come to mind:

1) checkbox in braille config dialog, for "via USB converter" - if checked, use
/dev/USB[0-3] or equivalent instead of /dev/ttys[0-3]

2) provide a combo-box for the serial device type, with entries such as 'ttys',
'ttyUSB', etc. and combine the result with the port number from the port
combo-box.  Provide a tooltip to help the user figure out that 'ttys' is
standard, 'ttyUSB' is suggested for most USB-to-serial converters.  There should
probably be an entry box provided as part of the combo, so that users can
specify some other device string to be concatenated with "/dev/" and the device
number.

Created attachment 50129 [details] [review]
proposed patch

This is a early patch focused on the UI change. The functionality is missing
for now.

Makes sense, to get it in before the string freeze.  Looks good to me.  Still,
it is a (small) UI change, so I imagine checking with the UI team for their OK
is needed.

The patch was approved and applied to CVS HEAD.
The code behind the UI will come soon.

Created attachment 50784 [details] [review]
the code behind the UI

Patch applied to cvs head.