diff --git a/MainForm.Designer.cs b/MainForm.Designer.cs
index 6be232e..e550bb0 100644
--- a/MainForm.Designer.cs
+++ b/MainForm.Designer.cs
@@ -73,8 +73,6 @@ namespace VideoPreview
             this.label1.TabIndex = 3;
             this.label1.Text = "File Name";
             this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
-            this.label1.DragDrop += new System.Windows.Forms.DragEventHandler(this.Form1_DragDrop);
-            this.label1.DragOver += new System.Windows.Forms.DragEventHandler(this.Form1_DragOver);
             // 
             // label2
             // 
@@ -85,8 +83,6 @@ namespace VideoPreview
             this.label2.TabIndex = 5;
             this.label2.Text = "-";
             this.label2.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
-            this.label2.DragDrop += new System.Windows.Forms.DragEventHandler(this.Form1_DragDrop);
-            this.label2.DragOver += new System.Windows.Forms.DragEventHandler(this.Form1_DragOver);
             // 
             // button1
             // 
@@ -120,8 +116,6 @@ namespace VideoPreview
             this.tHorizontalSeparator1.Size = new System.Drawing.Size(454, 22);
             this.tHorizontalSeparator1.TabIndex = 9;
             this.tHorizontalSeparator1.TabStop = false;
-            this.tHorizontalSeparator1.DragDrop += new System.Windows.Forms.DragEventHandler(this.Form1_DragDrop);
-            this.tHorizontalSeparator1.DragOver += new System.Windows.Forms.DragEventHandler(this.Form1_DragOver);
             // 
             // tHorizontalSeparator3
             // 
@@ -152,8 +146,6 @@ namespace VideoPreview
             this.flowLayoutPanel1.Size = new System.Drawing.Size(433, 540);
             this.flowLayoutPanel1.TabIndex = 1;
             this.flowLayoutPanel1.WrapContents = false;
-            this.flowLayoutPanel1.DragDrop += new System.Windows.Forms.DragEventHandler(this.Form1_DragDrop);
-            this.flowLayoutPanel1.DragOver += new System.Windows.Forms.DragEventHandler(this.Form1_DragOver);
             // 
             // pictureBox1
             // 
@@ -200,7 +192,6 @@ namespace VideoPreview
             this.button2.Size = new System.Drawing.Size(37, 37);
             this.button2.TabIndex = 2;
             this.toolTip1.SetToolTip(this.button2, "Options");
-            this.button2.MouseClick += new System.Windows.Forms.MouseEventHandler(this.button2_MouseClick);
             // 
             // button3
             // 
@@ -217,7 +208,6 @@ namespace VideoPreview
             this.button3.Size = new System.Drawing.Size(35, 37);
             this.button3.TabIndex = 3;
             this.toolTip1.SetToolTip(this.button3, "Refresh");
-            this.button3.MouseClick += new System.Windows.Forms.MouseEventHandler(this.button3_MouseClick);
             // 
             // button4
             // 
@@ -234,7 +224,6 @@ namespace VideoPreview
             this.button4.Size = new System.Drawing.Size(37, 37);
             this.button4.TabIndex = 4;
             this.toolTip1.SetToolTip(this.button4, "Next");
-            this.button4.MouseClick += new System.Windows.Forms.MouseEventHandler(this.button4_MouseClick);
             // 
             // label4
             // 
@@ -420,8 +409,6 @@ namespace VideoPreview
             this.MainMenuStrip = this.menuStrip1;
             this.Name = "MainForm";
             this.Text = "Video Preview";
-            this.DragDrop += new System.Windows.Forms.DragEventHandler(this.Form1_DragDrop);
-            this.DragOver += new System.Windows.Forms.DragEventHandler(this.Form1_DragOver);
             ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();
             this.menuStrip1.ResumeLayout(false);
             this.menuStrip1.PerformLayout();
diff --git a/MainForm.cs b/MainForm.cs
index d5a1263..d0f4e21 100644
--- a/MainForm.cs
+++ b/MainForm.cs
@@ -27,6 +27,10 @@ namespace VideoPreview
         {
             InitializeComponent();
 
+            button3.Click += delegate { refreshToolStripMenuItem_Click(null, null); };
+            button4.Click += delegate { loadNextFileToolStripMenuItem_Click(null, null); };
+            button2.Click += delegate { optionsToolStripMenuItem_Click(null, null); };
+
             button2.SetIcon("settings");
             button3.SetIcon("refresh-cw");
             button4.SetIcon("arrow-right-circle");
@@ -56,31 +60,17 @@ namespace VideoPreview
             base.OnFormClosing(e);
         }
 
-
-        public bool IsBusy
+        protected override void OnDragOver(DragEventArgs e)
         {
-            get => isBusy;
-            set
-            {
-                isBusy = value;
+            base.OnDragOver(e);
 
-                ThreadControl.SetValue(pictureBox1, (isBusy ? UIcon.GetImage("loading_block") : null));
-                ThreadControl.SetEnable(textBox1, !isBusy);
-                ThreadControl.SetEnable(button1, !isBusy);
-                ThreadControl.SetEnable(button2, !isBusy);
-                ThreadControl.SetEnable(button3, !isBusy);
-                ThreadControl.SetEnable(button4, !isBusy);
-            }
-        }
-
-
-        private void Form1_DragOver(object sender, DragEventArgs e)
-        {
             e.Effect = (e.Data.GetDataPresent(DataFormats.FileDrop) ? DragDropEffects.Copy : DragDropEffects.None);
         }
 
-        private async void Form1_DragDrop(object sender, DragEventArgs e)
+        protected override async void OnDragDrop(DragEventArgs e)
         {
+            base.OnDragDrop(e);
+
             string[] fileList = e.Data.GetData(DataFormats.FileDrop) as string[];
             if (fileList == null)
             {
@@ -110,31 +100,101 @@ namespace VideoPreview
         }
 
 
+        public bool IsBusy
+        {
+            get => isBusy;
+            set
+            {
+                isBusy = value;
+
+                ThreadControl.SetValue(pictureBox1, (isBusy ? UIcon.GetImage("loading_block") : null));
+                ThreadControl.SetEnable(textBox1, !isBusy);
+                ThreadControl.SetEnable(button1, !isBusy);
+                ThreadControl.SetEnable(button2, !isBusy);
+                ThreadControl.SetEnable(button3, !isBusy);
+                ThreadControl.SetEnable(button4, !isBusy);
+            }
+        }
+
         public AppSession CurrentSession { get; set; } = new AppSession();
 
 
-#region main menu
-
         /// <summary>
         /// Refresh
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
-        private void refreshToolStripMenuItem_Click(object sender, EventArgs e) => button3_MouseClick(null, null);
+        private async void refreshToolStripMenuItem_Click(object sender, EventArgs e)
+        {
+            if (this.IsBusy)
+            {
+                return;
+            }
+
+            if (string.IsNullOrWhiteSpace(textBox1.Text))
+            {
+                return;
+            }
+
+            await ReadVideoFile(textBox1.Text);
+        }
 
         /// <summary>
         /// Load next file
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
-        private void loadNextFileToolStripMenuItem_Click(object sender, EventArgs e) => button4_MouseClick(null, null);
+        private async void loadNextFileToolStripMenuItem_Click(object sender, EventArgs e)
+        {
+            if (this.IsBusy)
+            {
+                return;
+            }
+
+            if (string.IsNullOrWhiteSpace(textBox1.Text))
+            {
+                return;
+            }
+
+            await Task.Run(() =>
+            {
+                string path = AccessibleDirectory.GetNextFile(textBox1.Text, "*.avi;*.mkv;*.mp4;*.ogm;*.mov;*.mpg;*.mpeg");
+                if (string.IsNullOrWhiteSpace(path)) return;
+
+                textBox1.Text = path;
+            });
+        }
 
         /// <summary>
         /// Options
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
-        private void optionsToolStripMenuItem_Click(object sender, EventArgs e) => button2_MouseClick(null, null);
+        private void optionsToolStripMenuItem_Click(object sender, EventArgs e)
+        {
+            if (this.IsBusy)
+            {
+                return;
+            }
+
+            if (optionsForm == null) optionsForm = new OptionsForm(this.CurrentSession);
+            if (optionsForm.ShowDialog() == DialogResult.OK)
+            {
+                this.CurrentSession = optionsForm.Session;
+
+                this.TopMost = this.CurrentSession.AlwaysOnTop;
+            }
+        }
+
+        /// <summary>
+        /// Always-On-Top
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        private void toolStripMenuItem3_Click(object sender, EventArgs e)
+        {
+            this.TopMost = this.CurrentSession.AlwaysOnTop = !this.TopMost;
+        }
 
         /// <summary>
         /// View help
@@ -167,61 +227,6 @@ namespace VideoPreview
             MessageBox.Show(Application.ProductName + " v" + Application.ProductVersion, "About", MessageBoxButtons.OK, MessageBoxIcon.Information);
         }
 
-#endregion
-
-        /// <summary>
-        /// Refresh
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        private async void button3_MouseClick(object sender, MouseEventArgs e)
-        {
-            if (this.IsBusy) return;
-            if (string.IsNullOrWhiteSpace(textBox1.Text)) return;
-
-            await ReadVideoFile(textBox1.Text);
-        }
-
-        /// <summary>
-        /// Options
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        private void button2_MouseClick(object sender, MouseEventArgs e)
-        {
-            if (this.IsBusy)
-            {
-                return;
-            }
-
-            if (optionsForm == null) optionsForm = new OptionsForm(this.CurrentSession);
-            if (optionsForm.ShowDialog() == DialogResult.OK)
-            {
-                this.CurrentSession = optionsForm.Session;
-
-                this.TopMost = this.CurrentSession.AlwaysOnTop;
-            }
-        }
-
-        /// <summary>
-        /// Next file
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        private async void button4_MouseClick(object sender, MouseEventArgs e)
-        {
-            await Task.Run(() =>
-            {
-                if (this.IsBusy) return;
-                if (string.IsNullOrWhiteSpace(textBox1.Text)) return;
-
-                string path = AccessibleDirectory.GetNextFile(textBox1.Text, "*.avi;*.mkv;*.mp4;*.ogm;*.mov;*.mpg;*.mpeg");
-                if (string.IsNullOrWhiteSpace(path)) return;
-
-                textBox1.Text = path;
-            });
-        }
-
         /// <summary>
         /// Close
         /// </summary>
@@ -329,10 +334,13 @@ namespace VideoPreview
 
         protected async Task ReadVideoFile(string filename)
         {
+            if (this.IsBusy)
+            {
+                return;
+            }
+
             await Task.Run(() =>
             {
-                if (this.IsBusy) return;
-
                 this.IsBusy = true;
 
                 Clear();
@@ -415,9 +423,5 @@ namespace VideoPreview
             });
         }
 
-        private void toolStripMenuItem3_Click(object sender, EventArgs e)
-        {
-            this.TopMost = !this.TopMost;
-        }
     }
 }