The Desktop Layout in Welcome does not seem to have a preview mode with full revert to the pre-preview setup. I assume that MATE Tweak does the same. In most desktops, if one chooses to look at a different layout, one finds that upon examination, if one then choose to revert, the previous desktop is saved and restored. Thus, I preveiwed a different layout: my Workspace Switcher is 3 by 3; after revert, it was 9 x 1 (9 horizontal, 1 vertical). Other things also changed, and I had to use MATE Tweak to manually restore what I wanted. Moreover, there appeared to be no-inheritance -- my pre-preview layout of panels and the rest did not inherit to the new one (I did not try either the MacOS or MS Win style desktops), and were not restored upon revert. I strongly urge the developers/maintainers to consider both a proper full restore, and an inherit in so far as possible to the desktop layout under consideration. If a particular layout (say, the MacOS style) does not support some feature (panel, workspace switcher) then the disappearance of that feature from the layout under test might cause the user not to to use that particular layout. In many equivalent preview methods, the user is prompted with a phrase such as "keep the new layout?" If yes, just in case a key or touchscreen "bounced", there is a confirm second "yes"; if no, the desktop reverts to what is was before the preview.
