Public Function GetColumnDefinitionIndexFromColumnIndex( _
   ByVal columnIndex As Integer _
) As Integer

Dim instance As FilterColumnDefinitionCollection
Dim columnIndex As Integer
Dim value As Integer
 
value = instance.GetColumnDefinitionIndexFromColumnIndex(columnIndex)

public int GetColumnDefinitionIndexFromColumnIndex( 
   int columnIndex
)

FarPoint.Win.Spread.FilterColumnDefinitionCollection fcdc = new FarPoint.Win.Spread.FilterColumnDefinitionCollection();
FarPoint.Win.Spread.NamedStyle instyle = new FarPoint.Win.Spread.NamedStyle();
FarPoint.Win.Spread.NamedStyle outstyle = new FarPoint.Win.Spread.NamedStyle();
instyle.BackColor = Color.Yellow;
outstyle.BackColor = Color.Aquamarine;
FarPoint.Win.Spread.FilterColumnDefinition fcd = new FarPoint.Win.Spread.FilterColumnDefinition(1, FarPoint.Win.Spread.FilterListBehavior.SortByMostOccurrences
|  
FarPoint.Win.Spread.FilterListBehavior.Default);
FarPoint.Win.Spread.FilterColumnDefinition fcd1 = new FarPoint.Win.Spread.FilterColumnDefinition(2, FarPoint.Win.Spread.FilterListBehavior.Default);
FarPoint.Win.Spread.FilterColumnDefinition fcd2 = new FarPoint.Win.Spread.FilterColumnDefinition(3);
fcdc.Add(fcd);
fcdc.Add(fcd1);
fcdc.Add(fcd2);
FarPoint.Win.Spread.StyleRowFilter sf = new FarPoint.Win.Spread.StyleRowFilter(fpSpread1.ActiveSheet, instyle, outstyle);
foreach(FarPoint.Win.Spread.FilterColumnDefinition x in fcdc)
{
sf.AddColumn(x);
}
fpSpread1.ActiveSheet.RowFilter = sf;

int c = fcdc.GetColumnDefinitionIndexFromColumnIndex(1);
textBox1.Text = c.ToString();

Dim instyle As New FarPoint.Win.Spread.NamedStyle
Dim outstyle As New FarPoint.Win.Spread.NamedStyle
instyle.BackColor = Color.Yellow
outstyle.BackColor = Color.Aquamarine

Dim fcdc As New FarPoint.Win.Spread.FilterColumnDefinitionCollection
Dim fcd As New FarPoint.Win.Spread.FilterColumnDefinition(1, FarPoint.Win.Spread.FilterListBehavior.SortByMostOccurrences
Or FarPoint.Win.Spread.FilterListBehavior.Default)
Dim fcd1 As New FarPoint.Win.Spread.FilterColumnDefinition(2, FarPoint.Win.Spread.FilterListBehavior.Default)
Dim fcd2 As New FarPoint.Win.Spread.FilterColumnDefinition(3)
fcdc.Add(fcd)
fcdc.Add(fcd1)
fcdc.Add(fcd2)

Dim sf As New FarPoint.Win.Spread.StyleRowFilter(fpSpread1.ActiveSheet, instyle, outstyle)
Dim x As FarPoint.Win.Spread.FilterColumnDefinition
For Each x In fcdc
sf.AddColumn(x)
Next
fpSpread1.ActiveSheet.RowFilter = sf

Dim c As Integer = fcdc.GetColumnDefinitionIndexFromColumnIndex(1)
TextBox1.Text = c.ToString()