[BRLTTY] Filter keyboard keypresses on Linux

[Dave Mielke]

[quoted lines by Mario Lang on 2008/01/15 at 03:04 +0100]

>Yes, select the keyboard based on the bindings the user configured.
>I.e., if I have a binding for KEY_HELP, it does not make
>sense to select a keyboard without that key.

Perhaps, but perhaps not. Let's say you come up with a really cool set of 
bindings, and only some use KEY_HELP. Now you share your bindings with someone 
else whose keyboard doesn't have KEY_HELP. Should that be possible with those 
particular bindings being ignored, or should your entire set of bindings cause 
the other user's keyboard to be passed over? Mightn't a little bit of fault 
tolerance in the capability be useful?

>> Does anyone know what happens if the same event device is opened more than 
>> once, which could happen, for example, if more than one brltty is started?
>
>I *think* if the application does not "grab" the keyboard,
>other apps can still open the device.  I never tested
>what happens if a grabbed keyboard gets opened a second time,
>but that should be fairly easy to test with a custom piece of C code.
>I am currently swamped with work, so I could look at this
>case on the weekend at the earliest.

I've already tested this at this point. The device can be opened any number of 
times, but only one can grab. A subsequent grab yields EBUSY.

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