Found my problem.. Registered event handler using EventManager twice and in first case, was clearing selected items collection.  so this has been all my fault since first suggestion.  I apologize for the causing the confusion.

I slightly modified sample and it is doing what I want.   Added CellClickAction of SelectRecord and 

changed handler as you originally proposed without toggling Selected state.  So need to figure out why it is not doing this in my app.

Thanks.

Vlad, this sample does not do what you describe.  If I select multiple records with Ctrl + click and right click on another record, previously selected records are unselected but right clicked record is selected.  However, If I continue to right click, i keep adding records to the selected collection.  

Also, if I select multiple records using Ctrl + click, I do not see these in the "Selected Records" listbox.  

Please, find the attached sample that seems to work fine on my side.

When you run the sample, you can use the Ctrl key and the mouse left button to select the first three records for example. Then, when you right click on another record it is added to the selected records collection, keeping the previous selection . If you need to clear the last selected records then you can use the Clear method on the SelectedItems.Records collection as follows:

if (drp.Record != null)

{

xdg1.SelectedItems.Records.Clear();

drp.IsActive = true;

drp.Record.IsSelected = !drp.Record.IsSelected;

}

Let me know if this is what you are looking for.

Vlad, any new suggestions for this request/