Public Class frmDynPanel
 
    Private HorLineColor As Color = Color.DodgerBlue
    Private HorNo As Integer = 0
    Private ContextName As String
 
    Dim dlgColor As New ColorDialog
    Dim WithEvents ncmdaddsephor As New Button _
        With {.Parent = Me, .Text = "New Panel", .Width = 150}
 
    Dim allowdrag As Boolean = True
 
    Private Sub NcmdAddHorSep_Click(sender As Object, _
         e As EventArgs) Handles NcmdAddSepHor.Click
 
        If allowdrag Then
            HorNo += 1
 
            Dim ColorContext As New ContextMenuStrip _
                With {.Name = "Sep" & HorNo.ToString}
 
            AddHandler ColorContext.Opening, _
                     AddressOf ColorContext_Opening
 
 
            Static hgt As Integer = 0
            hgt += 15
 
            Dim np As New Panel
 
            np.Name = ColorContext.Name
            np.Parent = Me
            np.Size = New Size(200, 10)
            np.Location = _
               New Point(CInt((Width / 2) - (np.Width / 2)), _
                         CInt((Height / 2) - (np.Height / 2) + hgt))
            AddHandler np.Paint, AddressOf np_Paint
 
            np.ContextMenuStrip = ColorContext
            Controls.Add(np)
            np.BringToFront()
        End If
    End Sub
 
 
    Private Sub ColorContext_Opening(sender As Object, e As EventArgs)
 
        If dlgColor.ShowDialog <> DialogResult.Cancel Then
            HorLineColor = dlgColor.Color
            ContextName = DirectCast(sender, ContextMenuStrip).Name
            Refresh()
        End If
    End Sub
 
 
    Private Sub np_Paint(sender As Object, e As PaintEventArgs)
        Dim Pen As New Pen(Color.Black, 2)
        Dim pS As New Point(1, 1)   ' Start
        Dim pE As New Point(DirectCast(sender, Panel).Width - 1, 1)   ' End
 
        If DirectCast(sender, Panel).Name = ContextName Then
            Using HorPen As New Pen(HorLineColor, 2)
                e.Graphics.DrawLine(HorPen, pS, pE)
            End Using
        Else
            e.Graphics.DrawLine(Pen, pS, pE)
        End If
        Pen.Dispose()
    End Sub
End Class