Okay, if you can implement the 10 or more cursor position history of the cursor, you would not need an automatic generating of the bookmarks.
An automatic generating of the bookmarks is very similar to the page number of the code. The code is virtually divided to the pages (a code portion, which is fitted to the actual size of the main window). This allow jumping not just to the line number, but to the page number as well (might be useful in large files). When the Main Window is re-sized, then the so-called page-bookmarks are re-generated. I don't know how it's difficult to implement such feature ...
But, as for the cursor history 10 positions backward and forward, would you like to implement this feature. It could be very useful for the code navigation.
Thank you!