@AlexBell - thanks!
@The Old Man - at the bottom left of the page there is a button "go to last position" (there's also a back arrow in the bottom toolbar). This "undo to last position" behaviour is saved in Marvin in the following circumstances:
- You teleport to a different location in a book by tapping a hyperlink.
- You change locations by choosing a chapter/highlight/bookmark from the ToC screen.
- You flip multiple pages as once using "Smart Snapping" (
http://blog.marvinapp.com/post/62910719578).
- You scrub through the book using the slider at the bottom.
In other words, any action that could cause you to lose your current position. Marvin will not save the undo location if you flip pages one by one (it wouldn't make sense, since that's normal page turning behaviour).