Type: System.Int32 The number of columns visible in the viewport. The viewport is the rectangular area through which the grid is visible. The size of the viewport depends on the size of the System.Windows.Forms.DataGrid control; if you allow users to resize the control, the viewport will also be affected.
The number of visible columns can change depending on their width. For example, if a default width for all columns is set, but the width of a new column is set twice as large, the number of visible columns can be reduced by at least one.