Bug#1025775: libsdl2 breaks cataclysm-dda autopkgtest in lxc: only bottom left corner appears in screenshot

[Simon McVittie]

Control: reassign -1 src:cataclysm-dda 0.F-3-8
Control: tags -1 + patch

On Fri, 09 Dec 2022 at 17:58:38 +0000, Simon McVittie wrote:
> With SDL 2.26, it seems that under some circumstances (lxc but not qemu
> or podman, for some reason), the window won't become fullscreen without
> a window manager being present.

Bisecting SDL reveals that this was triggered by an intentional change,
<https://github.com/libsdl-org/SDL/commit/4ca7b378c5b831a82f1f0fa132939e8a3b6ac59a>.

Before that commit, SDL would set the window dimensions to the screen
size and also set the "please fullscreen" flag. However, this meant that
un-fullscreening a window would result in it still being screen-sized.

Since that commit, SDL sets the window dimensions to its non-fullscreen
size but sets the "please fullscreen" flag. A compatible window manager
will ignore the window dimensions and display the game full-screen, but
when the window leaves fullscreen, the window manager will use the
windowed dimensions automatically.

Assuming that full-screen will work as intended without a window manager
seems like a bug in cataclysm-dda's autopkgtest rather than a sign of
missing functionality in SDL, so I'm reassigning this to cataclysm-dda.
Please consider the attached patch, also available from
<https://salsa.debian.org/smcv/cataclysm-dda-branches/-/tree/autopkgtest-wm>
(git fetch https://salsa.debian.org/smcv/cataclysm-dda-branches autopkgtest-wm).

You might also find the changes in
<https://salsa.debian.org/smcv/cataclysm-dda-branches/-/tree/autopkgtest-misc>
useful for debugging and/or test robustness
(git fetch https://salsa.debian.org/smcv/cataclysm-dda-branches autopkgtest-misc).

    smcv
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