Re: [fltk.coredev] Fl_Choice initiates infinite loop

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Re: Fl_Choice initiates infinite loop imm 04:14 Jun 17 top right image
On Fri, 17 Jun 2022 at 11:44, Albrecht Schlosser wrote:
> On 6/17/22 01:58 Bill Spitzak wrote:
> > I think what is happening is the RELEASE event is getting lost, so the
> > counter thinks the button is pressed and keeps incrementing.
> Yes, that was my first thought too and my first demo program opened a
> modal window in the callback which directs the FL_RELEASE event to the
> modal window and thus it is lost for the Fl_Counter widget. But this is
> only one of the issues.

So... I haven't really been following this, but I'm concerned that
having a callback that runs for a significant time period might be a
tricky problem to solve anyway.

Whilst the button callback is "in flight" it seems that there could,
potentially, always be a risk of missing some events being delivered.
I think Windows tends to queue 'em all up, but I'm not sure to what
extent that happens for other OS, or how robust that really is...
Certainly on Windows if you block event delivery for "long enough"
things can start to get weird...

So it is useful to understand how/why the rebase event is getting lost
but I' also concerned that whatever we do may not be able to fix all
the cases.

Rob, if you break the timing dependency out - that is, have the button
cb return  "instantly" and then perform the time consuming
computations in a different thread (say) does that then make things
"work" - i.e. is it is possible to demonstrate that it is timing that
is the crux here, or is there something more going on?

> > ... but it would be possible for the counter to check if the mouse is
> > currently held down before repeating the timeout.
> That's something I'm definitely going to look at.

Though, reading this (and not knowing what is happening underneath!) I
was concerned that this may itself induce some aberrant behaviours...

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