Intermittently not getting release events (Windows 11)

[tkefauver]

TLDR: Is there a way with Sharphook to get an array, list, etc. of the current down keys? (as a workaround to this)

I'm using the SimpleGlobalHook with RunAsync and storing a list of down keys where I add the key (if not a repeat) in a KeyPressed handler and then remove it in a KeyReleased handler.

Intermittently a key will get 'stuck' where I never receive the release for a press and it seems to be completely random (could be any input or modifier key). I don't think its a problem w/ SharpHook but just can't figure out what's causing it!

These are the factors that maybe involved:

1. I'm testing on a dell laptop and thinking maybe it could related to using the Fn key (to use Home/End keys from the laptop arrows for example) and I do know that Fnby itself doesn't trigger a KeyPressed or KeyReleased which maybe unrelated but I figure its worth mentioning.
2. It seems to happen when I'm doing a lot of typing or keyboard navigating but that's all I know.
3. This is in an AvaloniaUI app (on Windows 11 22H2) and am going to ask a similar question on there github too because Avalonia's HotkeyManager maybe suppressing the KeyReleased from one of its KeyGestures internally somehow but my SimpleGlobalHook handles all the shortcuts and I would think it wouldn't be able to suppress globally but since its off the same main thread maybe it could be blocking it? Its so intermittent though so doesn't seem likely.

So my questions I suppose are these:

1. Is every down event supposed to have a corresponding up? Does pressing Shift for example when a key is down change its release KeyCode maybe?
2. Can other applications be suppressing the KeyRelease somehow? (like a Visual Studio thing? I don't have any global hot keys)
3. Since it seems to happen when I'm doing a lot of typing could the OS be blocking my handlers because they're taking too long? (They don't do that much processing, just comparing input to a few shortcuts right now and read here about blocking but this is only a release issue so not sure if that info is a factor here)

This has been a lingering bug for MONTHS so any insights would be appreciated 🙏

[TolikPylypchuk]

Hi! Thanks for asking! This looks like a problem with libuiohook, or even Windows itself. It sounds similar to issue #59 - what's described there is that a modifier key can get stuck in the pressed state. I will look into it.

As for your comments:

1. The Fn key is a hardware key, and as far as I know, even the OS doesn't handle it.
2. I think it's somehow related to message processing in Windows, but I'm not sure.
3. I don't think Avalonia has anything to do here, to be honest.

As for your questions:

1. Yes, when you press and release a key, it should emit a down event, and then an up event with the same key code.
2. Yes, they can - SharpHook provides this possibility as well. But I don't think that you have a global hook in your system which randomly suppresses key up events without your knowledge :)
3. I don't think it's necessarily related to your handler taking too long. If you want to test it out, you can use TaskPoolGlobalHook - unlike SimpleGlobalHook, it will run your event handlers in a separate thread, so it can take as long as it needs.

I'll convert this discussion into an issue since it looks like a bug which has to be fixed.

[TolikPylypchuk]

I've created issue #61

[tkefauver]

Ah ok thanks for taking the time let me know! I'll keep an eye on that issue now.