Undo-ing in a non-modal dialog

Question

I'm developing a graphical engineering application for desktop environments. As of today the application uses mostly non-modal dialogs that immediately commit the changes to the selected object. So the user can see the effects of the changes he made. In some cases it would be helpful if the user could undo these changes.

I'm seeking advice on how to best implement this from a UX point of view.

My ideas so far:

1. Add a "reset" button that replaces the current state with a saved state? But what point in time should be considered the last "correct" state?
2. Use the application's undo functionality? Every applied state of the dialog could be saved to the undo queue. But that doesn't seem to be very obvious to the user because he'd have to jump out of the dialog to perform that undo.
3. Add a "cancel" button that restores the state of the objects when the dialog was opened and closes the dialog? This would be very similar to a modal dialog. So:
4. Forget the idea of non-modal dialogs when rolling back complex changes is required?

Personally I'm leaning toward option 1 and use the object's state when it was selected as the good state.

Answer 1

Who are you designing for? If your users are tech savy. I would recommend just adding keyboard shortcuts like ctrl + z / cmd + z. (Even if they are not tech savy, keyboard shortcuts is universal) Just like you point out, they need to be able to control the "correct" state. In my opinion keyboard shortcut is more intuitive.

Answer 2

You're saying that your users would not know that if they close a dialogue box that the undo feature would not immediately make them think it would undo that last change? If so I disagree, this is the universal understanding of undo.

Now, if your concern is that you want the user to be able to undo states that are out of order, similar the photoshops history panel, then you should create this experience for them, however this is not intuitive at all and will be needless overhead on your product, this is why we don't see this history undo feature in all designs tools.

I disagree with the keyboard solution. Yes, this works for tech savvy people but why limit yourself? Also as a tech savvy person I make the assumption it does not work in any software other than office 365, whether that a good assumption or not, the point is I am tech savvy yet I wouldn't know about ctrl+z

I always fall back on universal patterns. You most likely have a utility bar, implement the pattern of undo, redo and save (unless you auto save).

I see this everywhere, Office 365, UX Pin, Adobe Products, YNAB.com, Invision, Sketch.

Implementing Ctrl+Z is still a viable solution but not means to an end.