diff --git a/src/kiri/core/frame.js b/src/kiri/core/frame.js
index 601f5cf63..317c82ee3 100644
--- a/src/kiri/core/frame.js
+++ b/src/kiri/core/frame.js
@@ -76,12 +76,19 @@ window.addEventListener('message', msg => {
         let bin = data.parse;
         let widget;
         switch ((data.type || 'stl').toLowerCase()) {
+            case 'ast':  //FreeCAD saves STL as ASCII when usint .ast extension
             case 'stl':
+		//in case stl is ASCII, this fails:
                 if (!bin.buffer) bin = new Float32Array(bin).buffer;
-                new load.STL().parse(bin, vertices => {
-                    platform.add(widget = newWidget().loadVertices(vertices));
-                    send({event: "parsed", data: [ widget.id ]});
-                });
+		//and we must not continue without any data at all, so revert:
+		if(bin.byteLength == 0) {
+		    bin = data.parse;
+		}
+		//arrow function is never called. Traditional works just fine:
+                let vertices = new load.STL().parse(bin);
+                platform.add(widget = newWidget().loadVertices(vertices));
+                send({event: "parsed", data: [ widget.id ]});
+
                 break;
             case 'obj':
                 // todo
@@ -101,6 +108,34 @@ window.addEventListener('message', msg => {
         }
     }
 
+
+    //uses data.widget_id to update widget from STL
+    if (data.update) {
+
+        let bin = data.update;
+        let widget;
+        switch ((data.type || 'stl').toLowerCase()) {
+            case 'ast':  //FreeCAD saves STL as ASCII when usint .ast extension
+            case 'stl':
+		//in case stl is ASCII, this fails:
+                if (!bin.buffer) bin = new Float32Array(bin).buffer;
+		//and we must not continue without any data at all, so revert:
+		if(bin.byteLength == 0) {
+		    bin = data.update;
+		}
+                let widget = api.widgets.map()[data.widget_id];
+                let vertices = new load.STL().parse(bin);
+                api.widgets.replace(vertices, widget);
+		//center the widget otherwise it will have odd movement limits:
+		widget.center();
+                send({event: "updated", data: [ widget.id ]});
+                break;
+        }
+    }
+
+
+
+
     if (data.load) {
         platform.load(data.load, (verts, widget) => {
             send({event: "loaded", data: [ widget.id ]});
diff --git a/src/kiri/core/selection.js b/src/kiri/core/selection.js
index f5fb2a91d..415877de8 100644
--- a/src/kiri/core/selection.js
+++ b/src/kiri/core/selection.js
@@ -138,8 +138,8 @@ function duplicate() {
         const bb = mesh.getBoundingBox();
         const ow = widget;
         const nw = api.widgets.new().loadGeometry(mesh.geometry.clone());
-        nw.meta.file = ow.meta.file;
-        nw.meta.vertices = ow.meta.vertices;
+        //meta should be cloned entirely to also copy additional data attached here:
+	nw.meta = ow.meta;
         nw.anno = ow.annotations();
         nw.move(bb.max.x - bb.min.x + 1, 0, 0);
         api.platform.add(nw, true);
diff --git a/src/kiri/run/frame.js b/src/kiri/run/frame.js
index 9830b4369..7cdb8c2ea 100644
--- a/src/kiri/run/frame.js
+++ b/src/kiri/run/frame.js
@@ -26,6 +26,13 @@
         }
     }
 
+    function dispatchMessage(msg) {
+        let { origin, source, target, data } = msg;
+        if (source.window === cwin) {
+            recv(msg);
+        }
+    }
+
     let API = KIRI.frame = {
         setFrame: (io, target) => {
             let type = typeof(io);
@@ -35,12 +42,12 @@
                 case 'object': setFrame(io); break;
                 default: throw `invalid frame type ${type}`;
             }
-            window.addEventListener('message', msg => {
-                let { origin, source, target, data } = msg;
-                if (source.window === cwin) {
-                    recv(msg);
-                }
-            });
+
+	    //changed eventListener to a named function here:
+	    //adding eventListeners with anonymous functions is bad practice
+	    //as it is impossible to prevent them from being more than once!
+ 	    window.removeEventListener('message', dispatchMessage);
+	    window.addEventListener('message', dispatchMessage);
         },
 
         send: send,
@@ -51,6 +58,9 @@
 
         parse: (data, type) => { send({ parse: data, type })},
 
+	//update widget with id widget_id from STL data:
+        update: (data, type, widget_id) => { send({ update: data, type, widget_id })},
+
         get: (scope) => { send({ get: scope })},
 
         setMode: (mode) => { send({ mode }) },