Private Declare Function GetForegroundWindow Lib "user32.dll" () As Int32
    Private Declare Function GetWindowText Lib "user32.dll" Alias "GetWindowTextA" (ByVal hwnd As Int32, ByVal lpString As String, ByVal cch As Int32) As Int32


Public Function GetActiveWindowTitle() As String
        Dim MyStr As String
        MyStr = New String(Chr(0), 100)
        GetWindowText(GetForegroundWindow, MyStr, 100)
        MyStr = MyStr.Substring(0, InStr(MyStr, Chr(0)) - 1)

        Return MyStr
    End Function

Dim nWnd As IntPtr
     
'nWnd contiene el handle
nWnd = FindWindow(Nothing, GetActiveWindowTitle)

  Private Sub Pic_Graf1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Pic_Graf1.Paint
       
        Dim Superficie As Graphics
        Dim Lapiz As Pen
        Dim RectanguloSuperior As Rectangle
        Dim RectanguloInferior As Rectangle
        Dim RectanguloRelleno As Rectangle
        Dim Relleno As SolidBrush
        Dim Fuente As Font

        If ActivateGraph_1 = False Then
            Pic_Graf1.Image = My.Resources._50px_error
            Me.Refresh()
            Exit Sub
        Else
            Pic_Graf1.Image = Nothing
        End If

        Superficie = e.Graphics
        Lapiz = New Pen(Color.Black, 2)

        Relleno = New SolidBrush(Color.Gray)
        Fuente = New Font("Arial", 12, FontStyle.Bold)
        RectanguloSuperior = New Rectangle(5, 5, 100, 50)
        RectanguloInferior = New Rectangle(5, 15, 100, 50)
        RectanguloRelleno = New Rectangle(10, 30, 95, 15)
        Superficie.FillRectangle(Relleno, RectanguloRelleno)
        Superficie.FillEllipse(Relleno, RectanguloInferior)

        Dim Valor1 As Integer = iPorcent_1_1
        Dim Valor2 As Integer = iPorcent_1_2
        Dim Valor3 As Integer = iPorcent_1_3
        Dim Valor4 As Integer = iPorcent_1_4

        Dim Porcent1 As Integer
        Dim Porcent2 As Integer
        Dim Porcent3 As Integer
        Dim Porcent4 As Integer

        Porcent1 = (Valor1 * 360) / 100
        Porcent2 = ((Valor2 * 360) / 100)
        Porcent3 = ((Valor3 * 360) / 100)
        Porcent4 = ((Valor4 * 360) / 100)

        'Rellena las secciones con diferentes colores
        Relleno.Color = pic_ref1.BackColor
        Superficie.FillPie(Relleno, RectanguloSuperior, 0, Porcent1)

        Relleno.Color = pic_ref2.BackColor
        Superficie.FillPie(Relleno, RectanguloSuperior, Porcent1, Porcent2)

        Relleno.Color = pic_ref3.BackColor
        Superficie.FillPie(Relleno, RectanguloSuperior, Porcent1 + Porcent2, Porcent3)

        Relleno.Color = pic_ref4.BackColor
        Superficie.FillPie(Relleno, RectanguloSuperior, Porcent1 + Porcent2 + Porcent3, Porcent4)
    End Sub