When the grid is in group by mode, say I have 2 groups

group 1 contained 4 items and group 2 contained 5 items

when you click a row in the group 1. i need to show the total rows in the group (in this case its 4) and also the selected row count. like (1 of 4)

if group 2 items are selected the it should be 1 of 5, 2 of 5.

How can i get the total rows from the each Active group? (Active group is the one which contained the active row. )

Thank you