Fix: Controllers contain no data

Vocaluxe.UI/BasicElements/Button/CUiElementButton.cs

@@ -5,9 +5,14 @@ namespace Vocaluxe.UI.BasicElements.Button
 {
     public class CUiElementButton:CUiElement
     {
-        public CControllerElementButton Controller => new CControllerElementButton();
+        public CControllerElementButton Controller { get; private set; }
         public override CController BasicController => Controller;
 
+        public CUiElementButton()
+        {
+            Controller = new CControllerElementButton();
+        }
+
         public static CUiElementButton CreateInstance(Dictionary<string, string> properties, IEnumerable<(CUiElement, string)> children)
         {
             return CUiElement.CreateInstance<CUiElementButton>(properties, children);