Finish bell implementation

[judah]

Finish the bell implementation:

• Get visual/audio bells working on Windows
• Get visual bell working on some POSIX terminal with the flash capability

[judah]

OK, the reason that the visual bell doesn't work on my machine is that when terminfo uses putChar it doesn't prevent buffering, which messes up the timing. Problem is, Haskeline wants stdout to be line buffered to prevent cursor flickers.

One possibility: tPuts checks whether the output string has a delay in it, and if so either:

• flushes after each character, or
• temporarily sets the console to NoBuffering?.

Note: I should test this against both my current ncurses and a different one that doesn't use time delays (instead outputs characters based on ostream).

Also: maybe terminfo should substitute a flash capability if the terminal doesn't provide one itself?

[judah]

On Windows, the audible beep from outputting "\a" seems so annoying that I'm not sure it's even worth having.

[judah]

OK, the visual bell now works on POSIX.

[anonymous]

Audible bell works on Win32 now. Using the MessageBeep? function produces a much nicer effect that's configurable in the Sound Control Panel.

[judah]

The relevant Win32 functions for implementing a visual bell "flash" manually appear to be:

FillConsoleAttribute
ReadConsoleOutputAttribute