Unlike editing forms for submission, where discarding the data with a Cancel nav button makes sense, that would be weird for editing files.

I’d opt for

• simply removing the Done button like other editors do when editing
• add Cancel to the right (! not where the non-destructive back button is usually) when adding a new capture

That would make sense to me.

I hadn't thought of it as editing a file since I always use it just to create the note, but of course you're right that in general that same window is also used for editing notes, so it wouldn't make sense for the back button to discard a pre-existing note you're editing.

I played with the app around some more. What I said holds true for Captures. When you edit item bodies in outlines, though, you can argue that you do have a form-like situation and want to be able to discard changes. I think that'd be reasonable, but the MobileOrg team may disagree :)

If an already existing capture is edited there should be an cancelling option.

I think Cancel & Done make sense when you are about to create a new "Capture". But for editing? There always is undo when you make mistakes while you type. (A dedicated undo button seems to be the new cool, by the way.) It's only an assumption: I think people rarely start editing an existing note and then want to cancel the whole process, rather preferring auto-saving of changes they make. (For what it's worth, a cancel button also is less consistent with existing iOS apps.)

From my point of view existing captures are item bodies residing in some kind of inbox.

Having the option to use an undo button seems fine for me. Using undo and then back would result in cancel, wouldn't it?

I think that this is a bad idea to straddling two worlds. MobileOrg as an application to handle notes and to work with notes, so, let's follow the rules for notes and in-place editing (Notes.app is a good example). In this case, it would be easier for users to work with it because the UX will be familiar. There are no reasons to mix different patterns.

I propose the following changes according to the discussion above and #193:

• Remove the Done button from the capture screen and keep only the "+" button to create a new note quickly;
• Do not save the note if it is empty;
• Use system-wide UX solutions for the Undo (double-tap with three fingers, swipe left with three fingers to Undo, right for Redo on iOS 13 or "shake").