This is just a quick update to let you know that, after many requests, stating with version 1.30, Undo-Redo functionality was added to Moments Designer on the page editor.
If you changed something by mistake or deleted an element that you weren't supposed to delete, this will come in handy, just hit that Undo button from the top main toolbar and return your design to a previous state, before that accidental action.
The same with the Redo function, return your design to a later state. This is a great way to evaluate different layouts, just Undo/Redo between them and choose the one that fits better.
As already mentioned, the Undo/Redo redo buttons are located on the top main toolbar, on the page editor screen, the first two "arrow" buttons. You can also use CTRL+Z hotkey to invoke an undo action. For redo, use CTRL+Y key combination.
You can learn more about Moments Designer on the product page and related blog posts.