sometimes i drag in a new component where it pushes neighboring components down, then i decide i want something else and hit ⌘+Z to go back.
what's great is almost everything is reverted even code changes in component options, or repositioning of components themselves.
the behavior i'm observing is the moved neighboring components don't return to their previous positions after ⌘+Z 
I confirm I've seen the same behavior. I'm not a big fan of the undo function as sometimes it doesn't seem to do anything and I'm not quite sure what is it that it's undoing.
yeah more than half the time, it ends up re-opening browser tabs regardless whether i have an actively-selected retool component /head-scratch
We created a report for this issue and we'll update you here when it's fixed. Thank you for your feedback! 
Any updates on this? It's still a major issue in the current cloud version. Half the time the undo button does nothing, making it impossible to undo any errors. The components are skipped over and it only undoes code changes.
Hi @lpearl, welcome to the forum! 
No updates yet. Thanks for your feedback, I added it to the report.