By default, the control contains no columns. Before adding new items, you need to add columns. Use the Add property to add new columns to the control. The control fires the AddColumn event is fired when a new columns has been added to Columns collection. Use the Caption property to change the column's caption. Use the HTLMCaption property to display the column's caption using HTML tags. To hide a column use the Visible property of the Column object. Use the AddItem, InsertItem, InsertControlItem, PutItems, DataSource properties to add new items to the control. Use the BeginUpdate and EndUpdate methods to maintain performance while adding new columns and items. Use the ConditionalFormats method to apply formats to a cell or range of cells, and have that formatting change depending on the value of the cell or the value of a formula.

The following VB sample adds columns from a record set:

Set rs = CreateObject("ADODB.Recordset")
rs.Open "Orders", "Provider=Microsoft.Jet.OLEDB.3.51;Data Source= D:\Program Files\Microsoft Visual Studio\VB98\NWIND.MDB", 3 ' Opens the table using static mode
Tree1.BeginUpdate
' Add the columns
With Tree1.Columns
For Each f In rs.Fields
    .Add f.Name
Next
End With
Tree1.PutItems rs.getRows()
Tree1.EndUpdate

The following VC sample adds a column:

#include "Columns.h"
#include "Column.h"
CColumns columns = m_tree.GetColumns();
CColumn column( V_DISPATCH( &columns.Add( "Column 1" ) ) );
column.SetHeaderBold( TRUE );

The following VB.NET sample adds a column:

With AxTree1.Columns
    With .Add("Column 1")
        .HeaderBold = True
    End With
End With

The Add method returns a Column object in a VARIANT value, so you can use a code like follows:

With AxTree1.Columns
    Dim c As EXTREELib.Column
    c = .Add("Column 1")
    With c
        .HeaderBold = True
    End With
End With

this way, you can have the properties of the column at design time when typing the '.' character.

The following C# sample adds a column:

EXTREELib.Column column = axTree1.Columns.Add( "Column 1" ) as EXTREELib.Column;
column.HeaderBold = true;

The following VFP sample adds a column:

with thisform.Tree1.Columns.Add( "Column 1" )
	.HeaderBold = .t.
endwith