[DllImport("user32.dll")]
private static extern uint GetGuiResources(IntPtr folyamat, uint jelzo);

private List<long> elozmeny = new List<long>();

private int GdiObjektumok()
{
    using (Process p = Process.GetCurrentProcess()) { return (int)GetGuiResources(p.Handle, 0); }
}

private long PrivatMemoriaMB()
{
    using (Process p = Process.GetCurrentProcess())
    {
        p.Refresh();
        return p.PrivateMemorySize64 / (1024 * 1024);
    }
}

private void tmrMeres_Tick(object sender, EventArgs e)
{
    long mb = PrivatMemoriaMB();

    elozmeny.Add(mb);

    if (elozmeny.Count > 120) { elozmeny.RemoveAt(0); }

    tsslMeres.Text = "Memória: " + mb + " MB   GDI-objektumok: " + GdiObjektumok();
    pnlGrafikon.Invalidate();
}

private void pnlGrafikon_Paint(object sender, PaintEventArgs e)
{
    Graphics g = e.Graphics;
    g.Clear(Color.White);

    if (elozmeny.Count < 2) { return; }

    long max = Math.Max(1, elozmeny.Max());
    PointF[] pontok = new PointF[elozmeny.Count];

    for (int i = 0; i < elozmeny.Count; i++)
    {
        pontok[i] = new PointF(i * (pnlGrafikon.Width - 1f) / (elozmeny.Count - 1), pnlGrafikon.Height - 1 - elozmeny[i] * (pnlGrafikon.Height - 2f) / max);
    }

    using (Pen toll = new Pen(Color.SteelBlue, 2)) { g.DrawLines(toll, pontok); }
}

private void Kiserlet(Action munka)
{
    pnlKiserletek.Enabled = false;

    try { munka(); }
    finally { pnlKiserletek.Enabled = true; }
}

private void btnBitmapSzivarog_Click(object sender, EventArgs e)
{
    Kiserlet(() =>
    {
        for (int i = 0; i < 100; i++)
        {
            Bitmap b = new Bitmap(1000, 1000);   // SZÁNDÉKOSAN hibás: nincs Dispose

            using (Graphics g = Graphics.FromImage(b)) { g.DrawLine(Pens.Black, 0, 0, 999, 999); }
        }
    });
}

private void btnBitmapUsing_Click(object sender, EventArgs e)
{
    Kiserlet(() =>
    {
        for (int i = 0; i < 100; i++)
        {
            using (Bitmap b = new Bitmap(1000, 1000))
            using (Graphics g = Graphics.FromImage(b))
            {
                g.DrawLine(Pens.Black, 0, 0, 999, 999);
            }
        }
    });
}

private void btnGdiSzivarog_Click(object sender, EventArgs e)
{
    Kiserlet(() =>
    {
        for (int i = 0; i < 1000; i++) { Graphics g = pnlGrafikon.CreateGraphics(); }   // SZÁNDÉKOSAN hibás
    });
}

private void btnGdiUsing_Click(object sender, EventArgs e)
{
    Kiserlet(() =>
    {
        for (int i = 0; i < 1000; i++) { using (Graphics g = pnlGrafikon.CreateGraphics()) { } }
    });
}

private void btnGc_Click(object sender, EventArgs e)
{
    GC.Collect();
    GC.WaitForPendingFinalizers();
    GC.Collect();
}

private void KepCsere(bool helyes)
{
    for (int i = 0; i < 200; i++)
    {
        Bitmap uj = new Bitmap(600, 400);

        using (Graphics g = Graphics.FromImage(uj)) { g.Clear(Color.FromArgb(i, 255 - i, 128)); }

        Image regi = pbKep.Image;

        pbKep.Image = uj;

        if (helyes && regi != null) { regi.Dispose(); }
    }
}

private void btnKepHelyes_Click(object sender, EventArgs e) { Kiserlet(() => KepCsere(true)); }
private void btnKepSzivarog_Click(object sender, EventArgs e) { Kiserlet(() => KepCsere(false)); }

private void btnFelszabaditott_Click(object sender, EventArgs e)
{
    RajzModell m = new RajzModell(100, 100);

    m.Dispose();

    try
    {
        Bitmap b = m.Kep;
    }
    catch (ObjectDisposedException ex)
    {
        tsslMeres.Text = "ObjectDisposedException: " + ex.ObjectName;
    }
}

private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
    if (pbKep.Image != null) { pbKep.Image.Dispose(); }
}