Controls: Add UnitTextBox

Elwig/Windows/AreaComAdminWindow.xaml.cs

@@ -25,7 +25,7 @@ namespace Elwig.Windows {
             };
             RequiredInputs = new Control[] {
                 FbNrInput, YearFromInput, KgInput, RdInput,
-                GstNrInput, AreaInput, AreaComTypeInput, WineCultivationInput
+                GstNrInput, AreaInput.TextBox, AreaComTypeInput, WineCultivationInput
             };
         }