fix node reinitialisation

src/plugin/manager.ts

@@ -387,12 +387,15 @@ class Visualization {
             this.depictionRoot.selectAll('*').remove();
             this.depiction = undefined;
             
+            this.nullNodesPositions();
             this.setupScene().then(() => this.centerScene());
         }
         else if (this.depiction === undefined) { 
+            this.nullNodesPositions();
             this.setupScene().then(() => this.centerScene());
         }
         else {
+            this.nullNodesPositions();
             this.setupLigandScene().then(() => this.centerScene());
         }
 
@@ -485,6 +488,16 @@ class Visualization {
         return 'blank.svg';
     }
 
+    private nullNodesPositions() { 
+        this.presentBindingSite.interactionNodes.forEach((x: Model.InteractionNode) => {
+            if (!x.static) {
+                x.fx = null;
+                x.fy = null;
+            }
+        });
+
+    }
+
     // #region fire events
 
     //https://stackoverflow.com/questions/40722344/understanding-d3-with-an-example-mouseover-mouseup-with-multiple-arguments