added something little, not that very important tho

Client/Views/LoginScreen.xaml

@@ -23,7 +23,7 @@
         <Label Grid.Row="2" FontSize="15" Content="(max amount of characters for the username is 10)"/>
 
         <TextBox Name="usernameTextbox" Grid.Row="1" Grid.Column="1" MaxLength="10" FontSize="30" VerticalAlignment="Center" HorizontalAlignment="Left" Width="250"/>
-        <Button Content="ENTER" Grid.Column="1" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Right" Width="100" Height="40" Click="Button_EnterUsername"/>
+        <Button Name="loginButton" Content="ENTER" Grid.Column="1" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Right" Width="100" Height="40" Click="Button_EnterUsername"/>
 
     </Grid>
 </Window>

Client/Views/LoginScreen.xaml.cs

@@ -28,6 +28,7 @@ namespace Client.Views
         {
             User user = new User(usernameTextbox.Text);
             Client client = new Client(user.Username);
+            loginButton.IsEnabled = false;
             client.OnSuccessfullConnect = () =>
             {
                 // because we need to start the main window on a UI thread, we need to let the dispatcher handle it, which will execute the code on the ui thread
@@ -41,6 +42,7 @@ namespace Client.Views
                 });
             };
 
+            
         }
     }
 }