some fixes

KopLab1/FormLibrary/CustomListBox.cs

@@ -45,15 +45,6 @@ namespace FormLibrary
         {
             SelectedItemChanged?.Invoke(this, EventArgs.Empty);
         }
-        public void PopulateListBox(ListBox listBox, List<string> items)
-        {
-            listBox1.Items.Clear();
-
-            foreach (var item in items)
-            {
-                listBox.Items.Add(item);
-            }
-        }
         public void PopulateListBox(List<string> items)
         {
             listBox1.Items.Clear();

KopLab1/FormLibrary/IntegerInputControl.cs

@@ -16,10 +16,8 @@ namespace FormLibrary
 {
     public partial class IntegerInputControl : UserControl
     {
-        // Событие, вызываемое при изменении значения в TextBox
         public event EventHandler? ValueChanged;
 
-        // Событие, вызываемое при изменении состояния CheckBox
         public event EventHandler? CheckBoxChanged;
 
         public IntegerInputControl()
@@ -57,18 +55,11 @@ namespace FormLibrary
             }
             set
             {
-                if (value == null)
+                if(value is not null) 
                 {
-                    checkBoxNull.Checked = true;
-                    textBoxInput.Enabled = false;
-                    textBoxInput.Text = string.Empty;
-                }
-                else
-                {
-                    checkBoxNull.Checked = false;
-                    textBoxInput.Enabled = true;
                     textBoxInput.Text = value.ToString();
                 }
+                checkBoxNull.Checked = value is null;
             }
         }
 

KopLab1/Forms/MainForm.cs

@@ -100,7 +100,7 @@ namespace Forms
             {
                 new Student { Group = "Пибд-33", FullName = "Иванов Иван Иванович", Course = 3 },
                 new Student { Group = "Пибд-33", FullName = "Петров Петр Петрович", Course = 2 },
-                new Student { Group = "Пибд-33", FullName = "Сидоров Сидор Сидорович", Course = 1 }
+                new Student { Group = "Пибд-33", FullName = "Антонов Антон Антонович", Course = 1 }
             };
 
             valueTableControl1.FillData(students);