An integer value that specifies the column's position among visible columns.
A column's visible order doesn't correspond to its position within the grid's GridControl.Columns collection. The column's visual position is specified by its VisibleIndex property. The column, whose VisibleIndex property value is set to 0 is leftmost within a grid, etc.
The VisibleIndex of the hidden columns (i.e. columns whose ColumnBase.Visible property is set to false) is -1.