This driver lets use a Graphical User Interface as BrlTTY device:
it behaves just like a real braille device, its cost excepted :)

It is mostly intended for sighted developers who don't have access to a real
device, but still want to have an idea of the accessiblity of their application.

Assuming you're under X, first launch brltty:
$ brltty -b xw -x as

Then you can launch a BrlAPI application:
$ ~/brltty/Programs/apitest
or you can launch text applications in AT-SPI terminals like gnome-terminal.

You may give several parameters to the driver:
$ brltty -b xw -t identity -B tkparms="-geometry -0+0 -display :1",lines=2,cols=20,model=bare
will set a 20x2 braille display appear in the upper right corner of the
:1 display, without any navigation key. There is also the vs model which
will show up most of VisioBraille device's keys.

You should configure your window manager not to let the BRLTTY window get
keyboard focus, so as to be able to simulate keypresses by pressing buttons.
Or you may use the -display tkparameter option to display the emulated device
on another X server and add the input=on option so that keypresses in the
device window will get simulated in the original display.

*** Don't set input=on without using -display too on a different display,
because else emulated keypresses will just loop ! ***

If you want braille display as well, you'll need the ClearlyU font
(included in recent xfonts-base packages) and a UTF-8 locale for
characters: if your usual locale is en_US, launch brltty with a
prepended LC_CTYPE:

LC_CTYPE=en_US.UTF-8 brltty ...