Sorry, the above process threw some warnings. I didn't notice them before:

Warning (emacs): Encountered (#<marker at 1 in *scratch*> . -14) entry in
undo list with no matching (TEXT . POS) entry



On 8 March 2017 at 23:38, nitish chandra <nitishchandrachinta@gmail.com>
wrote:

>
> Only marker originally pointing inside the deleted region were recorded
>> here, and this is to make sure they regain their previous position after
>> the reinsertion.
>>
>
> I removed this part of the code to see what changes.
>
> 1. I put a marker in a line
> 2. Deleted the line
> 3. Undo-ed the delete
>
> The marker is still in the proper place. So markers in the deleted string
> do seem to regain their position properly.
>