[BRLTTY] Show attributes, bug

[Lars Bjørndal]

Hello, developers!

If I turn on "Show attributes" in the "Preferences menu", and after a
while turn it off again, and if I save the configuration on exit, the
attributes dots are raised on the braille display. I needed to delete
the brltty-ht.prefs file and restart BRLTTY to work around it.

BTW it would be fine if at least some of the on/off options in the
"Preferences menu" could be accessed through key combinations on the
braille display. Wouldn't it?

Lars