A flag editor

Imports System<br />
Imports System.Drawing.Design<br />
Imports System.Windows.Forms<br />
Imports System.Windows.Forms.Design<br />
Imports System.ComponentModel<br />
Imports System.Drawing<br />
<br />
Namespace System.Design<br />
<br />
    Public Class FlagsEditor<br />
        Inherits UITypeEditor<br />
<br />
        Friend Class clbItem<br />
<br />
            Public Sub New(ByVal str As String, ByVal value As Integer, ByVal tooltip As String)<br />
                Me.str = str<br />
                Me._value = value<br />
                Me._tooltip = tooltip<br />
            End Sub<br />
            Private str As String<br />
            Private _value As Integer<br />
<br />
            Public ReadOnly Property Value() As Integer<br />
                Get<br />
                    Return _value<br />
                End Get<br />
            End Property<br />
            Private _tooltip As String<br />
<br />
            Public ReadOnly Property Tooltip() As String<br />
                Get<br />
                    Return _tooltip<br />
                End Get<br />
            End Property<br />
<br />
            Public Overloads Overrides Function ToString() As String<br />
                Return str<br />
            End Function<br />
        End Class<br />
        Private edSvc As IWindowsFormsEditorService = Nothing<br />
        Private clb As CheckedListBox<br />
        Private tooltipControl As ToolTip<br />
<br />
        Public Overloads Overrides Function EditValue(ByVal context As ITypeDescriptorContext, ByVal provider As IServiceProvider, ByVal value As Object) As Object<br />
            If Not (context Is Nothing) AndAlso Not (context.Instance Is Nothing) AndAlso Not (provider Is Nothing) Then<br />
                edSvc = CType(provider.GetService(GetType(IWindowsFormsEditorService)), IWindowsFormsEditorService)<br />
                If Not (edSvc Is Nothing) Then<br />
                    clb = New CheckedListBox<br />
                    clb.BorderStyle = BorderStyle.FixedSingle<br />
                    clb.CheckOnClick = True<br />
                    AddHandler clb.MouseDown, AddressOf Me.OnMouseDown<br />
                    AddHandler clb.MouseMove, AddressOf Me.OnMouseMoved<br />
                    tooltipControl = New tooltip<br />
                    tooltipControl.ShowAlways = True<br />
                    For Each name As String In [Enum].GetNames(context.PropertyDescriptor.PropertyType)<br />
                        Dim enumVal As Object = [Enum].Parse(context.PropertyDescriptor.PropertyType, name)<br />
                        Dim intVal As Integer = CType(Convert.ChangeType(enumVal, GetType(Integer)), Integer)<br />
                        If intVal > 0 Then<br />
                            Dim fi As System.Reflection.FieldInfo = context.PropertyDescriptor.PropertyType.GetField(name)<br />
                            Dim attrs As DescriptionAttribute() = CType(fi.GetCustomAttributes(GetType(DescriptionAttribute), False), DescriptionAttribute())<br />
                            Dim tooltip As String<br />
                            If attrs.Length > 0 Then<br />
                                tooltip = attrs(0).Description<br />
                            Else<br />
                                tooltip = ""<br />
                            End If<br />
                            Dim intEdited As Integer = CType(Convert.ChangeType(value, GetType(Integer)), Integer)<br />
                            Dim item As clbItem = New clbItem(enumVal.ToString, intVal, tooltip)<br />
                            Dim checkedItem As Boolean = ((intEdited And intVal) = intVal)<br />
                            clb.Items.Add(item, checkedItem)<br />
                        End If<br />
                    Next<br />
                    edSvc.DropDownControl(clb)<br />
                    Dim result As Integer = 0<br />
                    For Each obj As clbItem In clb.CheckedItems<br />
                        result = result Or obj.Value<br />
                    Next<br />
                    Return [Enum].ToObject(context.PropertyDescriptor.PropertyType, result)<br />
                End If<br />
            End If<br />
            Return value<br />
        End Function<br />
<br />
        Public Overloads Overrides Function GetEditStyle(ByVal context As ITypeDescriptorContext) As UITypeEditorEditStyle<br />
            Return UITypeEditorEditStyle.DropDown<br />
        End Function<br />
        Private handleLostfocus As Boolean = False<br />
<br />
        Private Sub OnMouseDown(ByVal sender As Object, ByVal e As MouseEventArgs)<br />
            If Not handleLostfocus AndAlso clb.ClientRectangle.Contains(clb.PointToClient(New Point(e.X, e.Y))) Then<br />
                AddHandler clb.LostFocus, AddressOf Me.ValueChanged<br />
                handleLostfocus = True<br />
            End If<br />
        End Sub<br />
<br />
        Private Sub OnMouseMoved(ByVal sender As Object, ByVal e As MouseEventArgs)<br />
            Dim index As Integer = clb.IndexFromPoint(e.X, e.Y)<br />
            If index >= 0 Then<br />
                tooltipControl.SetToolTip(clb, CType(clb.Items(index), clbItem).Tooltip)<br />
            End If<br />
        End Sub<br />
<br />
        Private Sub ValueChanged(ByVal sender As Object, ByVal e As EventArgs)<br />
            If Not (edSvc Is Nothing) Then<br />
                edSvc.CloseDropDown()<br />
            End If<br />
        End Sub<br />
    End Class<br />
End Namespace

enum Test
{
  ValueA = 1,
  ValueB = 2,
  ValueC = 4,
  ValueAB = ValueA | ValueB // 3
}