При запуске не видны кнопки на форме:
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Windows.Forms;
using NAudio.Wave;

namespace SlideshowApp
{
    public partial class MainForm : Form
    {
        private List imageFiles = new List();
        private int currentIndex = 0;
        private WaveOutEvent waveOut;
        private AudioFileReader audioFileReader;
        private Timer slideshowTimer;
        private bool isPlaying = false;

        // Для анимации
        private Timer animationTimer;
        private int animationStep;
        private int animationTotalSteps = 20;
        private Point startLocation;
        private Point endLocation;
        private PictureBox tempPictureBox;
        private TransitionEffect currentTransition = TransitionEffect.None;

        // Перечисление для типов переходов
        private enum TransitionEffect
        {
            None,
            SlideTopBottom,
            SlideRightLeft,
            SlideBottomTop
        }

        public MainForm()
        {
            InitializeComponent();
            InitializeSlideshow();
            InitializeAnimation();
            InitializeCheckBoxes();
        }

        private void InitializeSlideshow()
        {
            slideshowTimer = new Timer();
            slideshowTimer.Interval = 3000; // 3 секунды
            slideshowTimer.Tick += SlideshowTimer_Tick;
        }

        private void InitializeAnimation()
        {
            animationTimer = new Timer();
            animationTimer.Interval = 20; // Шаг анимации
            animationTimer.Tick += AnimationTimer_Tick;
        }

        private void InitializeCheckBoxes()
        {
            // Проверка, что CheckBox'ы уже добавлены на форму с именами:
            checkBoxSlideFromTop.CheckedChanged += CheckBoxSlideFromTop_CheckedChanged;
            checkBoxSlideFromRight.CheckedChanged += CheckBoxSlideFromRight_CheckedChanged;
            checkBoxSlideFromBottom.CheckedChanged += CheckBoxSlideFromBottom_CheckedChanged;
        }

        private void btnSelectFolder_Click(object sender, EventArgs e)
        {
            using (var folderBrowser = new FolderBrowserDialog())
            {
                if (folderBrowser.ShowDialog() == DialogResult.OK)
                {
                    imageFiles = Directory.GetFiles(folderBrowser.SelectedPath, "*.jpg").ToList();
                    currentIndex = 0;
                    ShowImage();
                }
            }
        }

        private void ShowImage()
        {
            if (imageFiles.Count > 0)
            {
                pictureBox.Image = Image.FromFile(imageFiles[currentIndex]);
                lblCounter.Text = $"{currentIndex + 1} / {imageFiles.Count}";
            }
        }

        private void btnNext_Click(object sender, EventArgs e)
        {
            if (imageFiles.Count == 0) return;

            int nextIndex = (currentIndex + 1) % imageFiles.Count;
            ShowNextImage(nextIndex, Direction.Next);
        }

        private void btnPrevious_Click(object sender, EventArgs e)
        {
            if (imageFiles.Count == 0) return;

            int prevIndex = (currentIndex - 1 + imageFiles.Count) % imageFiles.Count;
            ShowNextImage(prevIndex, Direction.Previous);
        }

        private void btnPlayPause_Click(object sender, EventArgs e)
        {
            if (isPlaying)
            {
                slideshowTimer.Stop();
                isPlaying = false;
                btnPlayPause.Text = "Play";
            }
            else
            {
                slideshowTimer.Start();
                isPlaying = true;
                btnPlayPause.Text = "Pause";
            }
        }

        private void SlideshowTimer_Tick(object sender, EventArgs e)
        {
            btnNext.PerformClick();
        }

        private void btnSelectMusic_Click(object sender, EventArgs e)
        {
            using (var openFileDialog = new OpenFileDialog())
            {
                openFileDialog.Filter = "MP3 Files|*.mp3";
                openFileDialog.Multiselect = true; // Позволяет выбрать несколько файлов
                if (openFileDialog.ShowDialog() == DialogResult.OK)
                {
                    PlayMusic(openFileDialog.FileNames.ToList());
                }
            }
        }

        private List musicFiles = new List();
        private int currentMusicIndex = 0;

        private void PlayMusic(List files)
        {
            musicFiles = files;
            currentMusicIndex = 0;
            PlayCurrentMusic();
        }

        private void PlayCurrentMusic()
        {
            if (currentMusicIndex >= musicFiles.Count)
                return;

            if (waveOut != null)
            {
                waveOut.Stop();
                waveOut.Dispose();
            }

            audioFileReader = new Aud