Aspect ratio of <https://hub.libreoffice.org/screenshots/*.png>

I'm not sure this is the best mailing list to discuss this issue.  Feel 
free to cc further mailing lists or relevant people.

We have a set of screenshots accessible via URLs like 
<https://hub.libreoffice.org/screenshots/writer-01.png> that are 
referenced from our AppData files (see the various 
sysui/desktop/appstream-appdata/libreoffice-*.appdata.xml sources, and 
solenv/bin/assemble-flatpak.sh generating a single such file for the 
Flatpak build).

Now, building LO 6.2.4 Flatpak on Flathub failed because Flathub started 
to sport a new check that verifies that such AppData screenshots have a 
16:9 aspect ratio.  I'm totally clueless as to how much sense such a 
check makes and whether it will continue to prevent us from providing an 
updated LO on Flathub, see the mail thread I started at 
<https://lists.freedesktop.org/archives/flatpak/2019-May/001582.html> 
"Run strict validation on AppData file" for details.

But in case we'll be forced to indeed provide 16:9 screenshots, I'd like 
to already clarify who'll be able to do that.  And whether those files 
would replace the existing 
<https://hub.libreoffice.org/screenshots/*.png> or would get fresh URLs.

The set of such .png files referenced from (current master) 
sysui/desktop/appstream-appdata/libreoffice-*.appdata.xml sources is

<https://hub.libreoffice.org/screenshots/base-01.png>
<https://hub.libreoffice.org/screenshots/base-02.png>
<https://hub.libreoffice.org/screenshots/calc-01.png>
<https://hub.libreoffice.org/screenshots/calc-02.png>
<https://hub.libreoffice.org/screenshots/draw-01.png>
<https://hub.libreoffice.org/screenshots/draw-02.png>
<https://hub.libreoffice.org/screenshots/impress-01.png>
<https://hub.libreoffice.org/screenshots/impress-02.png>
<https://hub.libreoffice.org/screenshots/writer-01.png>
<https://hub.libreoffice.org/screenshots/writer-02.png>

of which the Flatpak AppData file references only the five *-01.png.  So 
it would be great if at a minimum those five could be provided as 16:9 
if it turns out there's indeed need for that.