Proper fixed for multiple sidenav implemenations (Edges)

Author: kevzlou7979

gwt-material/src/main/java/gwt/material/design/client/base/AbstractSideNav.java

@@ -7,9 +7,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -38,6 +38,7 @@
 import gwt.material.design.client.js.JsSideNavOptions;
 import gwt.material.design.client.ui.*;
 import gwt.material.design.client.ui.html.ListItem;
+import gwt.material.design.jquery.client.api.JQueryElement;
 
 import static gwt.material.design.client.js.JsMaterialElement.$;
 
@@ -242,7 +243,6 @@ public void load() {
 
     @Override
     public void unload() {
-        $("#sidenav-overlay").remove();
         activator = null;
     }
 
@@ -402,6 +402,7 @@ protected MaterialWidget getNavMenu() {
 
     protected void onClosing() {
         open = false;
+        $("#sidenav-overlay").remove();
         SideNavClosingEvent.fire(this);
     }
 
@@ -411,13 +412,18 @@ protected void onClosed() {
 
     protected void onOpening() {
         open = true;
+
+        $("#sidenav-overlay").each((param1, element) -> element.removeFromParent());
         SideNavOpeningEvent.fire(this);
     }
 
     protected void onOpened() {
         if (allowBodyScroll) {
             RootPanel.getBodyElement().getStyle().clearOverflow();
         }
+
+        String overlayZIndex = $("#sidenav-overlay").css("zIndex");
+        $(".drag-target").css("zIndex", (overlayZIndex != null ? Integer.parseInt(overlayZIndex) : 1) + "");
         SideNavOpenedEvent.fire(this);
     }
 
@@ -552,6 +558,14 @@ public Element getActivator() {
         return activator;
     }
 
+    public JQueryElement getOverlayElement() {
+        return $("#sidenav-overlay");
+    }
+
+    public JQueryElement getDragTargetElement() {
+        return $(".drag-target");
+    }
+
     @Override
     public HandlerRegistration addOpeningHandler(SideNavOpeningEvent.SideNavOpeningHandler handler) {
         return addHandler(handler, SideNavOpeningEvent.TYPE);