To make Undo /Redo easier, I would really appreciate a list of the last few actions I’ve taken. This makes it very clear what the shortcut keys CTRL+Z / CTRL+Y (or ⌘ Z) are doing.

It can be confusing to spot what’s changed if it’s a settings change, or or minor visual change.

This feature is found in many graphics and CAD apps.

It usually appears in a pane on the right… and could include Undo/redo buttons.

Here’s a screenshot of what it looks like in paint.net (a very cheap/free graphics package!)