соединяет регистрацию с формой

AuthorizationForm.cs

@@ -22,9 +22,9 @@ namespace AwesomeEmailExtractor
             try
             {
                 Globals.currentUser = Authorization.Login(entryLogin.Text, entryPassword.Text);
-                this.Close();
 
-                new MainForm().Show();
+                var mainForm = FormManager.Current.CreateForm<MainForm>();
+                FormManager.Current.Navigate(this, mainForm);
             }
             catch (Exception ex)
             {
@@ -34,9 +34,8 @@ namespace AwesomeEmailExtractor
 
         private void registerButton_Click(object sender, EventArgs e)
         {
-            this.Close();
-
-            new RegistrationForm().Show();
+            var form = FormManager.Current.CreateForm<RegistrationForm>();
+            FormManager.Current.Navigate(this, form);
         }
     }
 }

AwesomeEmailExtractor.csproj

@@ -84,6 +84,7 @@
       <DependentUpon>AuthorizationForm.cs</DependentUpon>
     </Compile>
     <Compile Include="ExtactEmailsAlgorithm.cs" />
+    <Compile Include="FormManager.cs" />
     <Compile Include="Globals.cs" />
     <Compile Include="Logs.cs" />
     <Compile Include="MainForm.cs">

FormManager.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+namespace AwesomeEmailExtractor
+{
+    public class FormManager : ApplicationContext
+    {
+        private void onFormClosed(object sender, EventArgs e)
+        {
+            if (Application.OpenForms.Count == 0)
+            {
+                if (((Form)sender).Name == currentForm)
+                    ExitThread();
+            }
+        }
+        
+        public T CreateForm<T>() where T : Form, new()
+        {
+            var ret = new T();
+            ret.FormClosed += onFormClosed;
+            return ret;
+        }
+
+        public void Navigate(Form from, Form to)
+        {
+            currentForm = to.Name;
+            from.Close();
+            to.Show();
+        }
+
+        public string currentForm = "AuthorizationForm";
+
+        private static Lazy<FormManager> _current = new Lazy<FormManager>();
+        public static FormManager Current => _current.Value;
+
+        public FormManager()
+        {
+            var authorization = CreateForm<AuthorizationForm>();
+            authorization.Show();
+        }        
+    }
+}

Program.cs

@@ -20,9 +20,7 @@ namespace AwesomeEmailExtractor
 
             Application.EnableVisualStyles();
             Application.SetCompatibleTextRenderingDefault(false);
-
-            new AuthorizationForm().Show();
-            Application.Run();
+            Application.Run(FormManager.Current);
 
             postMain();
         }

RegistrationForm.Designer.cs

@@ -55,6 +55,7 @@
             this.entryPassword.Name = "entryPassword";
             this.entryPassword.Size = new System.Drawing.Size(195, 20);
             this.entryPassword.TabIndex = 10;
+            this.entryPassword.UseSystemPasswordChar = true;
             // 
             // label1
             // 
@@ -79,9 +80,10 @@
             this.registerButton.Location = new System.Drawing.Point(14, 135);
             this.registerButton.Name = "registerButton";
             this.registerButton.Size = new System.Drawing.Size(364, 23);
-            this.registerButton.TabIndex = 7;
+            this.registerButton.TabIndex = 6;
             this.registerButton.Text = "Зарегистрироваться";
             this.registerButton.UseVisualStyleBackColor = true;
+            this.registerButton.Click += new System.EventHandler(this.registerButton_Click);
             // 
             // loginButton
             // 
@@ -89,7 +91,7 @@
             this.loginButton.Location = new System.Drawing.Point(14, 187);
             this.loginButton.Name = "loginButton";
             this.loginButton.Size = new System.Drawing.Size(364, 23);
-            this.loginButton.TabIndex = 6;
+            this.loginButton.TabIndex = 7;
             this.loginButton.Text = "Авторизоваться";
             this.loginButton.UseVisualStyleBackColor = true;
             this.loginButton.Click += new System.EventHandler(this.loginButton_Click);
@@ -121,7 +123,6 @@
             this.label4.Size = new System.Drawing.Size(178, 18);
             this.label4.TabIndex = 14;
             this.label4.Text = "Уже зарегистрированы?";
-            this.label4.Click += new System.EventHandler(this.label4_Click);
             // 
             // RegistrationForm
             // 
@@ -140,6 +141,7 @@
             this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
             this.Name = "RegistrationForm";
             this.Text = "Зарегистрироваться";
+            this.FormClosed += new System.Windows.Forms.FormClosedEventHandler(this.RegistrationForm_FormClosed);
             this.ResumeLayout(false);
             this.PerformLayout();
 

RegistrationForm.cs

@@ -17,16 +17,36 @@ namespace AwesomeEmailExtractor
             InitializeComponent();
         }
 
-        private void label4_Click(object sender, EventArgs e)
+        private void registerButton_Click(object sender, EventArgs e)
         {
+            if (!string.Equals(entryPassword.Text, entryRePassword.Text))
+            {
+                MessageBox.Show("Пароли не совпадают!");
+                return;
+            }
 
+            try
+            {
+                Globals.currentUser = Authorization.Register(entryLogin.Text, entryPassword.Text);
+
+                var form = FormManager.Current.CreateForm<MainForm>();
+                FormManager.Current.Navigate(this, form);
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show(ex.Message);
+            }
         }
 
         private void loginButton_Click(object sender, EventArgs e)
         {
-            this.Close();
+            AuthorizationForm form = FormManager.Current.CreateForm<AuthorizationForm>();
+            FormManager.Current.Navigate(this, form);
+        }
 
-            new AuthorizationForm().Show();
+        private void RegistrationForm_FormClosed(object sender, FormClosedEventArgs e)
+        {
+            
         }
     }
 }