Hi ,

I came across an issue during the development of a business application, when using several XamWebGrid (2010.1) in a TabControl.

I made a little sample project that i attached to this message, where you can reproduce the problem. Here are the steps :

When the app is launched :

 - on the tabitem1 tab, make group by on 3 or 4 columns (drag column header)

 - Click the "add" button on the bottom right corner

- Go to the tabitem2 tab

- Come back on tabitem 1

- Choose a column to group by, and drag its header to the beginning of the group by area ( on the first group by header).

At this point i Get a NullReferenceException...

On my business app, i just need to drag the group by column header anywhere on the group by area to raise this exception, not only the beginning. But i can't manage to have a sample application that has the exact same problem. But still, it's almost the same :)

Thanx