Thank you. 

And stupid question - how do I move hidden columns?  This might be obvious for you but not so simple for me :)

Hi, 

Not a stupid question, i should have mentioned how :)

To move columns, you need to use the Columns collection, and the Add, Remove methods. 

For example:

ColumnBase col = grid.Columns[0];

grid.Columns.Remove(col);

grid.Columns.Add(col);

col.Visibility = Visibility.Collapsed. 

-SteveZ

This won't work. Here is my code:

void xGrid_GroupByCollectionChanged(object sender, GroupByCollectionChangedEventArgs e)

        {

            foreach (var col in xGrid.GroupBySettings.GroupByColumns)

            {

                xGrid.Columns.Remove(col);

                xGrid.Columns.Add(col);

                col.Visibility = Visibility.Collapsed;                

            }            

        }

And I still get the same exception. Is there something I'm doing wrong?

Hi, 

So, the scenario which you're attempting is a bit tricky b/c of that bug. 

However, the following code should pretty much do the trick. It might need some tweeks, but hopefully it should handle most situations. 

When the next SR comes out, this will no longer be necessary...instead you can just toggle the visibility. 

When the grid loads, store off all of the column indexes:

// Store off original indexes

                  int i = 0;

                  foreach (Column col in this.DataGrid1.Columns.DataColumns)

                  {

                        col.Tag = i;

                        i++;

                   } 

bool _ignoreEvent;

            void DataGrid1_GroupByCollectionChanged(object sender, GroupByCollectionChangedEventArgs e)

            {

                  if (!this._ignoreEvent)

                  {

                        // Removing a column, actually ungroups it, so while since we are doing this,

                        // we need to ignore each time the event fires during this operation.

                        List<Column> cols = new List<Column>(e.NewGroupedColumns);

                        foreach (Column col in cols)

                        {

                              _ignoreEvent = true;

                              this.DataGrid1.Columns.Remove(col);

                              this.DataGrid1.Columns.Add(col);

                              col.Visibility = Visibility.Collapsed;

                              col.IsGroupBy = true;

                              _ignoreEvent = false;

                        }

                        // The previous grouped columns contains what the list was previously.

                        // So find any columns that are no longer grouped, and restore their index, and visibility.

                        cols = new List<Column>(e.PreviousGroupedColumns);

                        foreach (Column col in cols)

                        {

                              if(!col.IsGroupBy)

                              {

                                    this.DataGrid1.Columns.Remove(col);

                                    int index = (int)col.Tag;

                                    this.DataGrid1.Columns.Insert(index, col);

                                    col.Visibility = Visibility.Visible;

                              }

                        }

                  }

            }

Hope this helps 

-SteveZ