public static AdvancedDropdown AddColumns(AddColumnsHandler addColumnsHandler, IEnumerable <SearchColumn> descriptors, Vector2 mousePosition, int activeColumnIndex)
        {
            var dropdown = new ColumnSelector(descriptors, "Select column...", addColumnsHandler, activeColumnIndex);

            dropdown.Show(new Rect(mousePosition.x, mousePosition.y, 1, 1));
            return(dropdown);
        }
        public ColumnSelector(IEnumerable <SearchColumn> descriptors, string title, AddColumnsHandler addColumnsHandler, int activeColumnIndex)
            : base(new AdvancedDropdownState())
        {
            m_Title             = title;
            m_Columns           = descriptors;
            m_AddColumnsHandler = addColumnsHandler;
            m_ActiveColumnIndex = activeColumnIndex;

            minimumSize = new Vector2(250, 350);
        }