The ExapndAll method expands all items in the editor's drop down list. Use the InsertItem method to insert child items to the editor's drop down list. Use the ExpandItem method to expand programmatically an item. The ExpandAll method has effect only if the EditType property is DropDownListType. Use the DropDownAutoWidth property to let the control computes the width of the drop down portion so all items hit the drop down client's area.

The following VB sample expands all items in the DropDownListType editor:

With Record1
    .BeginUpdate
    With .Add("DropDownList", EXRECORDLibCtl.DropDownListType)
        .DropDownAutoWidth = False
        .AddItem 0, "Root 1"
        .InsertItem 1, "Child 1", , 0
        .InsertItem 2, "Child 2", , 0
        .InsertItem 3, "SubChild 2.1", , 2
        .InsertItem 4, "SubChild 2.2", , 2
        .AddItem 5, "Root 2"
        .InsertItem 6, "Child 1", , 5
        .InsertItem 7, "Child 2", , 5
        .InsertItem 8, "SubChild 2.1", , 6
        .InsertItem 9, "SubChild 2.2", , 6
        .ExpandAll
        .Value = 6
    End With
    .EndUpdate
End With

The following VC sample expands all items in a DropDownListType editor:

COleVariant vtMissing; vtMissing.vt = VT_ERROR;
CEditor editor = m_record.Add(COleVariant("DropDownList"), /*DropDownListType*/ 3, vtMissing );
editor.SetDropDownAutoWidth( FALSE );
editor.AddItem( 0, "Root 1", vtMissing );
editor.InsertItem( 1, "Child 1", vtMissing, COleVariant( long(0) ) );
editor.InsertItem( 2, "Child 2", vtMissing, COleVariant( long(0) ) );
editor.InsertItem( 3, "SubChild 2.1", vtMissing, COleVariant( long(2) ) );
editor.InsertItem( 4, "SubChild 2.2", vtMissing, COleVariant( long(2) ) );
editor.AddItem( 5, "Root 2", vtMissing );
editor.InsertItem( 6, "Child 1", vtMissing, COleVariant( long(0) ) );
editor.InsertItem( 7, "Child 2", vtMissing, COleVariant( long(0) ) );
editor.InsertItem( 8, "SubChild 1.1", vtMissing, COleVariant( long(6) ) );
editor.InsertItem( 9, "SubChild 1.2", vtMissing, COleVariant( long(6) ) );
editor.SetValue( COleVariant( (long)6 ) );
editor.ExpandAll();