Size of Canvas / panel different from the Bitmap ?

Sub Globals
    Dim x00, y00, x01, y01 As Float
    Dim x10, y10, x11, y11 As Float

    Dim pnlSignature, pnlBitmap As Panel
    Dim cvsSignature, cvsBitmap As Canvas
    Dim btnOK As Button
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Dim x, y As Float
    
    btnOK.Initialize("btnOK")
    Activity.AddView(btnOK, 10, 10, 100, 60)
    btnOK.Text = "OK"
    
    pnlSignature.Initialize("pnlSignature")
    Activity.AddView(pnlSignature, 80, 80, 640, 400)
    pnlSignature.Color = Colors.Yellow
    cvsSignature.Initialize(pnlSignature)
    
    pnlBitmap.Initialize("")
    Activity.AddView(pnlBitmap, 320, 0, 160, 100)
    pnlBitmap.Color = Colors.White
    cvsBitmap.Initialize(pnlBitmap)
End Sub

Sub pnlSignature_Touch (Action As Int, X As Float, Y As Float) As Boolean
    
    Stroke = 2
    Select Action
    Case Activity.ACTION_DOWN
        x00 = X
        y00 = Y
        x10 = Max(Stroke, X / 4)        ' garanties at least one Stroke
        y10 = Max(Stroke, Y / 4)
    Case Activity.ACTION_MOVE
        x01 = X
        y01 = Y
        x11 = Max(Stroke, X / 4)
        y11 = Max(Stroke, Y / 4)
        Log(x00&" "&x01&" "&y00&" "&y01)
        cvsSignature.DrawLine(x00, y00, x01, y01, Colors.Black, 4)
        cvsBitmap.DrawLine(x10, y10, x11, y11, Colors.Black, Stroke)
        x00 = x01
        y00 = y01
        x10 = x11
        y10 = y11
        pnlSignature.Invalidate
        pnlBitmap.Invalidate
    End Select
    Return True
End Sub

Sub btnOK_Click
    Dim bdr As BitmapDrawable
    Dim bmp As Bitmap
    Dim destRect As Rect
    
    destRect.Initialize(0, 0, 160, 100)
    bdr = pnlBitmap.Background
    bmp = bdr.Bitmap
    cvsSignature.DrawBitmap(bmp,Null,destRect)
    pnlSignature.Invalidate
End Sub