Hi, 

You can't set the height of the GroupByBox, it's calculated automatically as needed.

You might want to look at grid.DisplayLayout.GroupByBox.Style which allows you to set the GroupByBox to Compact style and make it take up a little less room. 

There's no property for determining the height, either. But if the grid is displayed and has painted at least once, you could probably get the rect using UIElements.Something like this:

            UIElement gridElement = this.ultraGrid1.DisplayLayout.UIElement;
            if (gridElement != null)
            {
                UIElement groupByBoxUIElement = gridElement.GetDescendant(typeof(GroupByBoxUIElement));
                if (groupByBoxUIElement != null)
                    Debug.WriteLine(groupByBoxUIElement.Rect);
            }