Public Class Form1
    Dim g As Graphics
    Dim bDraw As Boolean
 
    Private Structure myPaintStruct
        Dim ptStart As Point
        Dim ptEnd As Point
    End Structure
 
    Dim myPaintList As New List(Of myPaintStruct)
    Dim colmyPaint As myPaintStruct
 
    Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Me.MouseDown
        colmyPaint.ptStart = e.Location
        myPaintList.Add(colmyPaint)
        bDraw = True
    End Sub
 
    Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove
        If bDraw = True Then
            colmyPaint = myPaintList.Item(myPaintList.Count - 1)
            colmyPaint.ptEnd = e.Location
            myPaintList.Item(myPaintList.Count - 1) = colmyPaint
            g = Me.CreateGraphics
            g.Clear(Color.LightBlue)
 
            For i As Integer = 0 To myPaintList.Count - 1
                g.DrawLine(Pens.Black, myPaintList.Item(i).ptStart.X, _
                  myPaintList.Item(i).ptStart.Y, myPaintList.Item(i).ptEnd.X, _
                  myPaintList.Item(i).ptEnd.Y)
            Next
        End If
    End Sub
 
    Private Sub Form1_MouseUp(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Me.MouseUp
        bDraw = False
    End Sub
End Class