bug#69246: 30.0.50; persistent key input delay after using vc commands in pgtk

[Nick OBrien via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

On Wednesday, February 21st, 2024 at 6:41 AM, Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Wed, 21 Feb 2024 02:19:11 +0000
> > From: Nick OBrien nick4f42@proton.me
> > Cc: 69246@debbugs.gnu.org
> > 
> > In other words, if I press and release a key at the same time, the lag isn't
> > noticeable. I only see the lag when I press a key and don't release it. When a
> > key is held down and auto-repeating, I don't notice a drastic speed difference
> > with or without the lag. The appearing characters just look choppier when the
> > lag is occurring.
> > 
> > I realize this is an awkward bug to explain and reproduce, thanks for bearing
> > with me. More suggestions on how to narrow down the cause would be appreciated.
> 
> 
> Isn't it expected that the key only appears when it's released? Po
> Lu, any comments to this strange issue?

I would think it's expected for the key to appear after pressing the key, not
releasing it.


On Wednesday, February 21st, 2024 at 6:49 AM, Po Lu <luangruo@yahoo.com> wrote:

> Do other GTK 3 programs exhibit this lengthening of the intervals
> between generated repeat keypresses? What if the environment variable
> GTK_IM_MODULE is set to `none'?
> 
> TIA.

Running "GTK_IM_MODULE=none emacs -Q" and following the steps in the original
bug report, the lag appears to be fixed. I reproduced it three times, and each
time there was no lag. For reference, I tried again with GTK_IM_MODULE=fcitx
(how it was in the original bug report) and 4/4 times I experienced the lag.

I haven't ever experienced this sort of lag in Firefox or signal-desktop, two
gtk3 apps I regularly use. And just to clarify, the lag doesn't seem to lengthen
the interval between generated repeat key-presses. The repeated key-presses just
seem /choppier/, as if the frame-rate is lower. The lag is most obvious when
holding down a key and releasing after a single key appears.

I'll try using my normal config with GTK_IM_MODULE=none and see if I experience
the lag in everyday use.

Thanks