Bug 199570 – [GTK] Blank web view when transitioning between hardware acceleration (composition) modes

• Status: NEW
• Component: WebKitGTK

WebKitGTK 2.24.2

I'm working on the WebKitGTK port of Next browser:
https://next.atlas.engineer.
(Mirror: https://github.com/atlas-engineer/next)

When I switch "buffer" (or "tab") between 1 page displaying https://imdb.com and
another displaying https://github.com, the github page is _very often_
blank (not always).  If I open a new tab for github, it works.

After a discussion with Michael Catanzaro, we presumed that the issue may lie in
the transition in and out of accelerated composition mode.

Indeed, if I start Next with WEBKIT_FORCE_COMPOSITING_MODE=1, the issue
disappears.

A work around would be to set it to "forced" with
webkit_settings_set_hardware_acceleration_policy(), but what about systems that
do not support hardware acceleration then?

The problem occurs on master (for posterity: commit e13f5b9ecd232aa780b636a0c873fdccc1be6f0d).

Could be related to
https://bugs.webkit.org/show_bug.cgi?id=193224.

[Michael Catanzaro]

It's not related to bug #193224 because PSON is not enabled in the 2.24 branch.

[Carlos Garcia Campos]

I can't reproduce it with 2.24.2, but there are a lot more issues with current trunk, it only works with AC disabled.

[Carlos Garcia Campos]

hmm, I guess I can't reproduce in 2.24 because AC is now forced in next.

[Carlos Garcia Campos]

I've found the problem in trunk, but I can't reproduce it in trunk even when not forcing AC mode yet.

Indeed, as a workaround I'm forcing AC in Next.
Force-disabling AC works too.  Only "auto" triggers the issue.

I'm not sure I understand the last comment: you found the problem, but it works with Next nonetheless?  Is there anything I can do to help?

[Carlos Garcia Campos]

I tried to reproduce the issue in current trunk patching next to not force AC mode, and I couldn't reproduce it. Neither with 2.24.

I'm running Next on Guix, if that can help reproducing the issue.
(Guix can be installed on any GNU/Linux distro.)

[Carlos Garcia Campos]

Wayland or X11?

X11.