How to do multi-select for ag-grid from related foundset

Questions
1

I have a grid that I want to show contents of a related foundset (detail from a master type).
I want to allow multiple selection in the grid.
I do not know how to get the multiple selected rows from the grid - or the equivalent of the selected indexes from the foundset that correspond to the multiple rows selected in the grid.
I thought I only had to set the related foundset property to allow mutliple selection - but this does not work in the grid - still does single selection.
I then thought I have to set the grid option rowSelection=‘multiple’ in the grid property. In the UI this does allow multiple selection but I cannot get the rows or the selected records from the grid - the ag-grid api seems not to be implemented?
I thought I should combine the two (in the foundset and in the grid) but nope.
If anyone has done this I would appreciate it.
This should be documented but I cannot find it in any searches.
The only search I found is in the ag-grid documentation to use their api to getSelectedNodes or rows.

Using Servoy 2020.12.3263

Tom

2

I did not get any replies to this question so I am posting my so-called workaround. Not sure if it s defect or a feature.
To get it to work:
the master - detail relation foundset also has a multi-select flag that must be set true.
I found out by adding a check whenever the master record is selected it will fire the appropriate relation to the detail. The check gets the multi-select flag from the relation and if false it will set to true.
This seems to work for my case.

var masterRec = masterFoundset.getSelectedRecord();
if(!masterRec.master_to_detail.multiSelect) {
        masterRec.master_to_detail.multiSelect = true;
}

I am not sure it is supposed to work this way.

I assume that on the first onRecordSelection event of the master that I can set the multi-select flag to true and forget about it. But no it does get reset to false every time!
Hope this helps others.
If this is incorrect please respond!
Tom