I have a grouping grid which including row expander. (Just like an attachment 3.png).

Now, I would like to append a summary row at the end of expanded group row. (Please refer to attachment 3.png).

I had tried to override the GroupingView function call "doGroupEnd" and append a new row to StringBuilder. However, I found that there is a problem if the grid called GridCellRender to render a button.

May I ask any other suggestion or sample to suggest me?

Many Thanks.