Hello,

There is no build functionality to set auto sizing based on the columns count in ColumnChooserControl. So you can try to set the size of the control  based on the columns count and multiply with the rows default height. See the code snipped bellow.:

void ultraGrid1_BeforeColumnChooserDisplayed(object sender, BeforeColumnChooserDisplayedEventArgs e)
        {
           …
           int newHeight = this.ultraGrid1.DisplayLayout.Bands[0].Columns.Count * 20;
           e.Dialog.Size = new Size(200, newHeight);
       …
        }

Let me know if that helps.

Sincerely,
Dimi
Developer Support Engineer
Infragistics, Inc.