Do not require ComboBoxes to be valid if they are not required

Elwig/Windows/ContextWindow.cs

@@ -1,14 +1,10 @@
 using Elwig.Helpers;
-using System;
-using System.Collections.Generic;
 using System.ComponentModel;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Windows;
 
 namespace Elwig.Windows {
     public abstract class ContextWindow : Window {
+
         protected readonly AppDbContext Context;
 
         public ContextWindow() : base() {