Re: [Gimp-gui] GTK3 "empty black window"/"black flash" bug that affects GIMP-2.99

[Jehan <jehan girinstud io>]

On 2018-08-04 13:50, Elle Stone wrote:
> Hi All,
>
> This is just an FYI for anyone who encounters the issue and doesn't
> already know about this bug.
>
> There is a long-standing GTK3 bug - that's recently been fixed in GTK
> git master - that does affect GIMP-2.99. I noticed it yesterday when I
> tried for the first time to use GIMP-2.99 for actual editing.
>
> This bug causes an empty black window to briefly appear when opening
> editing dialog windows such as "Filters/Blur/Gaussian Blur".
>
> FWIW, this GTK3 bug was reported back in 2015 for GTK3 version 3.22.x,
> and there is a trail of bug reports on various OS's running various
> desktops, including:
>
>     Black background appears briefly before window gets drawn:
>     https://bugzilla.gnome.org/show_bug.cgi?id=748498
>     https://gitlab.gnome.org/GNOME/gtk/issues/550
>
>     GTK3 windows appear with a black flash:
>     https://bugzilla.gnome.org/show_bug.cgi?id=771708
>     https://bugzilla.redhat.com/show_bug.cgi?id=1370791
>
>     Black background appears briefly before window gets drawn:
>     https://gitlab.gnome.org/GNOME/gtk/issues/550
>
> The fix was committed here, three months ago:
>
>     x11: Set a transparent background on windows by default
>     "This avoids black flicker on compositing WMs when a window is 
> first shown."
>
> https://gitlab.gnome.org/GNOME/gtk/commit/2ce63a86ba689aa41eb47409c889c469497478b0
>
> I noticed the "empty black window" bug when opening GIMP-2.99 editing
> dialogs such as "Curves" and "Gaussian Blur", on both Gentoo (updated
> a couple of week ago) and OpenSUSE Tumbleweed (updated today). Both of
> these OS's use GTK3 version 3.30.
>
> Checking the latest 3.30 tarball from
> http://ftp.gnome.org/pub/gnome/sources/gtk+/3.22/, it appears the fix
> hasn't been incorporated into any actual GTK3 releases.

I was wondering what you meant by 3.30. You meant 3.22.30, last release 
of 3.22.
Also I just checked, your commit is available in a release: 3.23.0 which 
is an unstable release.

We are actually waiting a bit to bump the dependency of GTK+ a bit, but 
we are planning to. I also wait for a fix I made (also available in 
3.23.0) and Mitch told me he also has a commit there.
So this bump will happen sooner rather than later, no problem. :-)

> So I downloaded the latest GTK3 tarball, applied the fix (involves
> adding a couple of extra lines of code to gdk/x11/gdkwindow-x11.c),
> and compiled/installed it in my GIMP-2.99 prefix. This fix does indeed
> get rid of the "black flash" problem.

You may also use the unstable tarballs from 3.23 so that you don't have 
to patch yourself. :-)
https://download.gnome.org/sources/gtk+/3.23/

Thanks anyway for this informative email!

Jehan

> Best,
> Elle
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