[Vm-dev] Multiple Keydown and up

David T. Lewis lewis at mail.msen.com
Wed Jan 6 21:38:51 UTC 2021


On Wed, Jan 06, 2021 at 04:27:45PM -0500, David T. Lewis wrote:
>  
> On Tue, Jan 05, 2021 at 09:22:58PM -0800, tim Rowledge wrote:
> >  
> > 
> > 
> > > On 2021-01-05, at 6:54 PM, Yoshiki Ohshima <Yoshiki.Ohshima at acm.org> wrote:
> > > 
> > > Hi,
> > > 
> > > Another  Raspberry Pi  Scratch issue report but possibly affects Squeak on other platforms.
> > > 
> > > A user reported that if you press down one key, and then another key, and then try to release both keys, the key up for the first key does not get reported.
> > > 
> > > https://youtu.be/N9q8DxYWAik
> > > 
> > > It could be the way Scratch handles them, but maybe it is an VM issue. Can somebody give me insight?\
> > 
> > It depends; is this the NuScratch as delivered in Raspbian? Or the package loaded into a post 5.1 image?
> > 
> > In experiments updating to a 5.3 image I notice that the  keyboard listener
> > I wroet way back when no longer seems to work as well. I do recall Marcel
> > doing work in that general area and changing how events are dealt with;
> > I'm guessing it will be related.
> > 
> > Scratch expects to see a state for each key, rather than handle events - in
> > *some* places. Sigh. Anything that makes the KeyboardStateWatcher class not
> > accurately track the key events will mess up some things. Or indeed, if I
> > made any mistakes or failed to catch every possible case, which must be
> > possible.
> > 
> 
> I'm sorry I cannot provide a reference, but I think that I recall some
> discussion of this in earlier years. It may be that this was caused by
> a limitation related to X11 key event delivery in the Unix VM. Possibly
> there is some discussion in the vm-dev archives. That's all I remember
> and it might be wrong.
>

Ugh, so as soon as I hit <send> I think of looking in the old Mantis
issue tracker. Here is the issue that I was remembering:

  http://bugs.squeak.org/view.php?id=7597

So it was a Unix VM bug that apparently got fixed in Cog. I am not sure
if this is same problem that we see today, but if so perhaps it is a
regression.

Note that the Mantis bug report includes HandMorph-handleEvent.st from
Matthew Fulmer that might be helpful in debugging the problem today.

Dave 


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