Option Strict On
Option Explicit On

Public Class comFlatComboBox
  Inherits ComboBox

  Private Const WM_PAINT As Integer = &HF
  Private Const WM_NCPAINT As Integer = &H85

  Private m_bolMouseDown As Boolean = False
  Private m_RectButton As Rectangle

  Public Sub New()
  End Sub

  Protected Overrides Sub OnMouseUp(ByVal e As MouseEventArgs)
    MyBase.OnMouseUp(e)
    m_bolMouseDown = False
    Invalidate()
  End Sub

  Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
    MyBase.OnMouseDown(e)
    m_RectButton = New Rectangle(Width - 18, 0, 17, Height)
    If e.X >= m_RectButton.Left Then
      m_bolMouseDown = True
      Invalidate()
    End If
  End Sub

  Protected Overrides Sub OnResize(ByVal e As EventArgs)
    MyBase.OnResize(e)
    Invalidate()
  End Sub

  Protected Overrides Sub WndProc(ByRef m As Message)
    Dim g As Graphics = Graphics.FromHwnd(Handle)

    Select Case m.Msg
      Case WM_NCPAINT
        g.Clear(BackColor)
      Case WM_PAINT
        MyBase.WndProc(m)
        g.DrawRectangle(New Pen(BackColor, 2), _
              New Rectangle(2, 2, Width - 4, Height - 4))
        m_RectButton = New Rectangle(Width - 18, 0, 17, Height)
        If m_bolMouseDown Then
          ControlPaint.DrawComboButton(g, m_RectButton, _
                ButtonState.Pushed)
        Else
          ControlPaint.DrawComboButton(g, m_RectButton, _
                ButtonState.Flat)
        End If
    End Select
    MyBase.WndProc(m)
    g.Dispose()
  End Sub
End Class