[Vm-dev] key-up events missing for some unix machines?

Ian Piumarta piumarta at speakeasy.net
Tue Nov 5 01:19:17 UTC 2013

On Nov 4, 2013, at 16:28 , tim Rowledge wrote:

> Interesting. I’m puzzled even more now since I see differences between the sqUnixX11.c in the Cog and plain trees, whereas I was until then convinced that they used the same platform code… sigh. 

The Qwak/Teleplace code is based on an ancient fork of the tree that was closed-source for several years while the trunk diverged.  That's why Cog still uses Makefiles and not CMake, etc...

I remember fixing an issue with auto-repeating meta keys a few years ago, which might have introduced the issue with n-key rollover and missing up events.  I'll take a look (especially promptly if you can provide a simple reproducible test case/scenario :-).

> However, I get the problem on the Pi with both a plain interp and a stack vm, so I’m going to have to suspect either a systemic problem or the USB.

I don't know if this is related but I've often had problems with X11 and the client being one event behind what the user is doing on the server.  Even when XSync()s are sprinkled in every conceivable place, some events just don't seem to make it into the dispatch loop when they are the last in the queue.  A typical symptom is a menu not seeing mouse up after you release the button, until you wiggle the cursor to generate some motion event pressure behind it.  One thing to look for is whether your missing up events appear if you wiggle the mouse immediately after releasing the key.

It's not just Squeak.  I've seen this issue with many X11 programs.  I'd suspect something fishy with NDELAY on the connection, but after so many years one would expect xlib to be getting that right.



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