How to set the colors of a color gradient in a control

Dim cor1 As Color = Color.SkyBlue
  Dim cor2 As Color = Color.Lime
  Private Sub TabPageExecutarPrograma_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles TabPageExecutarPrograma.Paint
    Dim FormGraphics As Graphics = e.Graphics
    Dim GradientBrush As Brush
    GradientBrush = New LinearGradientBrush(New Point(0, 0), New Point(0, Me.Height), cor1, cor2)
    FormGraphics.FillRectangle(GradientBrush, ClientRectangle)
  End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
   cor1 = Color.Blue
   cor2 = Color.Green
End Sub