Did you try using get(portalRowNumber) in place or get(recordNumber) ?
you might also have to use a multiplier for rows 2 and up (IE get(portalRowNumber) * 10, so it starts at 20, 30, 40, etc...)
I finally got this working for the most part, not sure if it will end up being ideal in the long run performance wise...
One flaw I just need to work out is having extra rows being displayed from the Find Results.
This is how I have it working now:
Each record contains a unique ID number which is related to itself through a calculation field shown below
GetNthRecord(Extend(Picture ID) ; Get(RecordNumber)*10 + Get(CalculationRepetitionNumber) - 10)
The calculation's repetition number is 10 in this case.
As for displaying results, the layout is displayed as list view with one row of 10 portals, each starting a new initial row. 1, 2, 3, 4... 10
It does return something like this...
list row 1 : 
list row 2 : 
list row 3 : [............................................]
However, I do believe due to having the multiplier shows many additional blank rows.
For example, a search result contains 120 records where the grid of results should have 12 rows, 10 records each. What is happening though, 120 rows are being returned, with the proper records on the first 12 rows... I am looking to find someway to hide/remove the extra rows... I've tried a script that omits rows 13 thru 120, but this has caused issues with the proper records being displayed.
the get(PortalRowNumber) doesn't work in my Filemaker ???
I get the message : "This parameter is an invalid Get function parameter"
I'm using FM12, also have a copy of FM 13, where it's not working either...
how can this be ?
It's context-sensitive, you need to have a row active in your portal for it to return a value, else I think it just returns zero.
Also, I think the function may have changed at some point in time to get(ActivePortalRowNumber), you might try that instead. Not sure if Get(PortalRowNumber) is still valid.
I saw somehting like this done by a guy a few years ago. There is a video on YouTube showing it in use as a photo management solution. I think he may work for Filemaker now. I have never figured out how he did it, but I believe it was using portals and not list view. I have been wanting somehting like this for a while but it is not at the top of my project list.