let drawGameBoard () =
        let bmp = new System.Drawing.Bitmap(fst GUI.BoardSize, snd GUI.BoardSize)
        let data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), Imaging.ImageLockMode.ReadWrite, bmp.PixelFormat)
        let adr x y = NativePtr.add<byte> (NativePtr.ofNativeInt data.Scan0) ((y*data.Stride) + (x*4))
        for cellX in { 0 .. fst GUI.CellCount - 1 } do
            for cellY in { 0 .. snd GUI.CellCount - 1 } do
                let color = if gameBoard.[cellX, cellY] = 1 then 0uy else 255uy
                for x in { 0 .. GUI.CellSize - 1 } do
                    for y in { 0 .. GUI.CellSize - 1 } do
                        let addr = adr (cellX * GUI.CellSize + x) (cellY * GUI.CellSize + y)
                        NativePtr.set addr 3 255uy
                        NativePtr.set addr 2 color
                        NativePtr.set addr 1 color
                        NativePtr.write addr color
        bmp.UnlockBits(data)
        GUI.gamePicture.Image <- bmp

    let mutable mouseDown = false
    let mutable downFill = 1

    // Handle clicks
    GUI.btnStep.Click.Add(fun _ -> if not !running then progressGame (); drawGameBoard ())
    GUI.btnRun.Click.Add(fun _ -> (GUI.btnRun.Text <- if !running then "Run" else "Stop"); running := not !running;)
    GUI.btnClear.Click.Add(fun _ -> running := false; (for x in { 0 .. fst GUI.CellCount - 1 } do for y in { 0 .. snd GUI.CellCount - 1 } do gameBoard.[x,y] <- 0); drawGameBoard())
    GUI.gamePicture.MouseDown.Add(fun e -> mouseDown <- true; if not !running then downFill <- clickGameBoard e.Location.X e.Location.Y)
    GUI.gamePicture.MouseUp.Add(fun _ -> mouseDown <- false)
    GUI.gamePicture.MouseMove.Add(fun e -> if mouseDown && not !running then
                                            if e.Location.X >= 0 && e.Location.Y >= 0 && e.Location.X <= fst GUI.BoardSize && e.Location.Y <= snd GUI.BoardSize
                                                && gameBoard.[e.Location.X/GUI.CellSize % fst GUI.CellCount, e.Location.Y/GUI.CellSize % snd GUI.CellCount] <> downFill then
                                                    let timer = new Stopwatch()
                                                    timer.Start()
                                                    ignore (clickGameBoard e.Location.X e.Location.Y)
                                                    timer.Stop()
                                                    printfn "%d ms" timer.ElapsedMilliseconds)