Yeah, I bit the bullet.

Imports System.Drawing.Design
Imports System.ComponentModel
Imports System.ComponentModel.Design

Public Class PathCollectionEditor
   Inherits CollectionEditor

   Public Sub New()
       MyBase.New(GetType(Generic.List(Of String)))
   End Sub

   Protected Overrides Function CreateCollectionItemType() As System.Type
       Return GetType(FolderPath)
   End Function

   Protected Overrides Function CanSelectMultipleInstances() As Boolean
       Return False
   End Function

   Protected Overrides Function GetDisplayText(ByVal value As Object) As String
       Dim displayText As String = String.Empty
       Dim folder As FolderPath = CType(value, FolderPath)
       Dim fld As String = folder.Path

       If (String.IsNullOrEmpty(fld) = False) Then
           Try
               Dim di As New IO.DirectoryInfo(fld)
               displayText = di.Name
           Catch ex As Exception
           End Try
       End If

       If (String.IsNullOrEmpty(displayText) = True) Then
           displayText = "[Folder]"
       End If

       Return displayText
   End Function

   Protected Overrides Function CreateCollectionForm() As System.ComponentModel.Design.CollectionEditor.CollectionForm
       Dim frm As CollectionEditor.CollectionForm = MyBase.CreateCollectionForm()
       frm.Font = New Font("Tahoma", 8.25!)
       frm.Text = "Edit Folders"
       frm.HelpButton = False

       'TableLayoutPanel: overArchingTableLayoutPanel
       '    Button: downButton
       '    TableLayoutPanel: addRemoveTableLayoutPanel
       '        Label: propertiesLabel
       '        Label: membersLabel
       '        FilterListBox: ListBox
       '        VsPropertyGrid: propertyBrowser
       '        TableLayoutPanel: okCancelTableLayoutPanel
       '        Button: upButton

       Dim overArchingTableLayoutPanel As TableLayoutPanel = frm.Controls.Item("overArchingTableLayoutPanel")
       If (Not overArchingTableLayoutPanel Is Nothing) Then
           Dim propertyBrowser As PropertyGrid = overArchingTableLayoutPanel.Controls.Item("propertyBrowser")
           If (Not propertyBrowser Is Nothing) Then
               propertyBrowser.PropertySort = PropertySort.Alphabetical
               propertyBrowser.ToolbarVisible = False
           End If
       End If

       'For Each ctrl As Control In frm.Controls.Item("overArchingTableLayoutPanel").Controls
       '    Debug.WriteLine(ctrl.Name, ctrl.GetType().Name)
       'Next

       Return frm
   End Function

   ''' <summary>
   ''' Gets the list of items to fill the editor.
   ''' </summary>
   ''' <param name="editValue">The source property</param>
   ''' <returns>Returns an IList items to populate the collection editor with.</returns>
   Protected Overrides Function GetItems(ByVal editValue As Object) As Object()
       'MsgBox(editValue.GetType().Name, , "GetItems")
       Dim lst As New Generic.List(Of FolderPath)
       For Each path As String In editValue
           lst.Add(New FolderPath(path))
       Next
       Return lst.ToArray()
   End Function

   ''' <summary>
   ''' Takes the items from the editor and reapplies them to the source property.
   ''' </summary>
   ''' <param name="editValue">The source property</param>
   ''' <param name="value">List of items from the editor.</param>
   Protected Overrides Function SetItems(ByVal editValue As Object, ByVal value() As Object) As Object
       'MsgBox(editValue.GetType().Name & ", " & value.GetType().Name, , "SetItems")
       Dim values As New Generic.List(Of String)
       Dim uniquity As New Generic.List(Of String)
       For i As Integer = 0 To value.Length - 1
           Dim o As Object = value(i)
           Dim path As String = String.Empty
           If TypeOf o Is String Then
               path = CStr(o)
           ElseIf TypeOf o Is FolderPath Then
               path = CType(o, FolderPath).Path
           End If
           If (String.IsNullOrEmpty(path) = False) Then
               If (uniquity.Contains(path.ToLower()) = False) Then
                   uniquity.Add(path.ToLower())
                   values.Add(path)
               End If
           End If
       Next
       Return MyBase.SetItems(editValue, values.ToArray())
   End Function

End Class

Public Class FolderPath

   Private _path As String = String.Empty

   <Editor(GetType(PathEditor), GetType(UITypeEditor))> _
   Public Property Path() As String
       Get
           Return Me._path
       End Get
       Set(ByVal Value As String)
           If (String.IsNullOrEmpty(Value) = True) Then Value = String.Empty
           Me._path = Value
       End Set
   End Property
   Private Function ShouldSerializePath() As Boolean
       Return False
   End Function
   Private Sub ResetPath()
       Me.Path = String.Empty
   End Sub

   Public Sub New()
   End Sub

   Public Sub New(ByVal path As String)
       MyClass.New()
       Me.Path = path
   End Sub

End Class

Public Class PathEditor
   Inherits UITypeEditor

   Public Sub New()
       MyBase.New()
   End Sub

   Public Overrides Function EditValue(ByVal context As System.ComponentModel.ITypeDescriptorContext, ByVal provider As System.IServiceProvider, ByVal value As Object) As Object
       Dim path As String = CStr(value)
       Dim dlg As New FolderBrowserDialog
       dlg.SelectedPath = path
       dlg.Description = "Select folder"
       Dim res As DialogResult = DialogResult.Cancel
       res = dlg.ShowDialog()
       If (res = DialogResult.OK) Then
           path = dlg.SelectedPath
       End If
       Return path
   End Function

   Public Overrides Function GetEditStyle(ByVal context As System.ComponentModel.ITypeDescriptorContext) As System.Drawing.Design.UITypeEditorEditStyle
       Return UITypeEditorEditStyle.Modal
   End Function

End Class