That looks really interesting - you’ve probably seen that we are keen to improve our layout designer experience (see Layout Designer Timeline Improvements). Our suggestion is slightly different from what you’ve produced, but we’re always open to suggestions!
The key part of our specification was to add a floating lower tool box for adding/assigning new and existing widgets to the designer - this would fit nicely in with your design too. It would show “modules” that can be added as widgets, library content and allow searching (opening new tabs in the toolbox so that you can remember searches across Layouts).
With regards to your design, I like the “timeline” style set of regions shown at the top - I guess that if you click on a widget it opens up in the “widget viewer” - effectively providing a scaled preview of that widget?
One of the things we are trying to do with the current designer is to provide a “complete” preview of the content, as it would be seen, side by side. I am guessing that you wouldn’t have a “live” preview in the “Layout Viewer” section - and that section is only designed to position the regions?
In any case we’re really keen to see it working and to potentially use it in the core product to replace the existing designer. We plan to do that for 1.9 release, including having the Playlists functionality working. Would it be possible to provide a copy so that we can see it working?
Thanks!
Dan