DockPanel.Item Property

public DockPanel this[ 
   int index 
] { get; }

Public ReadOnly Property Item( 
   ByVal index As Integer 
) As DockPanel

using DevExpress.XtraBars.Docking;
// ...
void DoSomeOperation(DockPanel panel) {
   //...
}

void IterateChildPanels(DockPanel parentPanel) {
   if(parentPanel == null) return;
   for(int i = 0; i < parentPanel.Count; i++) {
      DockPanel childPanel = parentPanel[i];
      if(childPanel.Count == 0)
         DoSomeOperation(childPanel);
      else
         IterateChildPanels(childPanel);
   }
}

Imports DevExpress.XtraBars.Docking
' ...
Sub DoSomeOperation(ByVal panel As DockPanel)
   '...
End Sub

Sub IterateChildPanels(ByVal parentPanel As DockPanel)
   If parentPanel Is Nothing Then Return
   Dim i As Integer
   For i = 0 To parentPanel.Count - 1
      Dim childPanel As DockPanel = parentPanel(i)
      If childPanel.Count = 0 Then
         DoSomeOperation(childPanel)
      Else
         IterateChildPanels(childPanel)
      End If
   Next
End Sub