Additional Fixed for Window - Add checks for errai support

Author: kevzlou7979

src/main/java/gwt/material/design/addins/client/window/MaterialWindow.java

@@ -111,6 +111,7 @@ public class MaterialWindow extends MaterialPanel implements HasCloseHandlers<Bo
     private MaterialAnimation closeAnimation;
 
     private MaterialDnd dnd;
+    private boolean initialized;
 
     public MaterialWindow() {
         super(AddinsCssName.WINDOW);
@@ -137,7 +138,10 @@ public MaterialWindow(String title, Color backgroundColor, Color textColor, Colo
     protected void onLoad() {
         super.onLoad();
 
-        initialize();
+        if (!initialized) {
+            initialize();
+            initialized = true;
+        }
     }
 
     /**
@@ -392,4 +396,4 @@ public void setDndArea(Object dndArea) {
             dnd.draggable(JsDragOptions.create(new Restriction(dndArea, true, 0, 0, 1.2, 1)));
         }
     }
-}
+}