Please add all panel layouts in MATE Tweaks
It seems like Ubuntu MATE is the only MATE GNU/Linux distro that includes MATE Tweak pre-installed out of the box AND all of the panel layouts including Redmond, Cupertino, etc.
I've seen in places such as here https://www.reddit.com/r/debian/comments/6qcyg5/debian_matetweak/ that it is possible to obtain and transfer those layouts from elsewhere, but why not build them in?
Is it because the Genie Effect in Cupertino requires video hardware acceleration and Trisquel switched from GNOME to MATE to avoid such requirement?
Please add all panel layouts in MATE Tweaks
I second that.
Specifically, I miss the Redmond panel layout
Redmond is present in Trisquel 9 MATE Tweaks, but Cupertino is not.
It turns out, there are several panel layouts installed but they are not directly accessible in the MATE TWEAKS menu. Inspired by this: https://ubuntu-mate.community/t/choosing-and-changing-panel-layouts-ubuntu-mate-18-04/16502 I found out that there are several configuration files for panel layouts in /usr/share/mate-panel.
I cannot choose them from the MATE TWEAK menu, but if you choose the custom layout, configuration files for it are made for it in the mate-panel folder. Renaming the configuration files for the layout of your choice with the name of the file names for the custom layout will make it accessible in the TWEAK MENU (as the custom layout). Remember to delete the files for the custom layout before renaming the files for the layout of your choice (two files can't have the same name).
In order to activate your desired panel layout, choose e.g. the Trisquel layout in the MATE TWEAK menu, and then choose the custom layout again. Voila.
Since you would have to follow this procedure for every change of panel layout, this is far from ideal but at least you can change panel layout by this cumbersome procedure.
I played with the Mate Tweak tool, and the panel was lost. To restore, type in terminal:
mate-panel --reset
Now it seems to work more or less as intended, restore is done using the GUI but the Trisquel panel is not quite the same as originally when first installed.
Three panel themes: Trisquel, Redmond, Traditional. You see, the Trisquel panel has a cog wheel that is not present in the default install.