Autofit by doubleclicking right side of header row . .

The default behavior is to restrict the resizing to the visible grid for performance reasons. If you want to remove this restrictions, you can subscribe to teh ResizingColumsn event and do the resizing yourself. If you want the doubleclick to behave differently, you can handle this event.

private void grid_ResizingColumns(object sender, GridResizingColumnsEventArgs e)
{
	if(e.Reason.Equals(GridResizeCellsReason.DoubleClick))
	{
		GridRangeInfo range = e.Columns; 
	this.grid.Model.ColWidths.ResizeToFit(range, 
                			GridResizeToFitOptions.IncludeHeaders);
		e.Cancel = true;
	}
}