Ensure UndoManager on components

src/canvas/model/Frame.js

@@ -44,8 +44,6 @@ export default Model.extend({
 
     !props.width && this.set(keyAutoW, 1);
     !props.height && this.set(keyAutoH, 1);
-
-    this.getComponent()._initUm();
   },
 
   changesUp: debounce(function(opt = {}) {

src/dom_components/model/Component.js

@@ -208,17 +208,31 @@ const Component = Backbone.Model.extend(Styleable).extend(
       });
 
       if (!opt.temporary) {
+        this.__postAdd();
         this.init();
         this.__isSymbolOrInst() && this.__initSymb();
         em && em.trigger('component:create', this);
       }
     },
 
-    _initUm() {
+    __postAdd(opts = {}) {
       const um = this.em.get('UndoManager');
-      if (!um) return;
-      um.add(this);
-      um.add(this.components());
+      const comps = this.components();
+      if (um && !this.__hasUm) {
+        um.add(this);
+        um.add(comps);
+        this.__hasUm = 1;
+      }
+      opts.recursive && comps.map(c => c.__postAdd(opts));
+    },
+
+    __postRemove() {
+      const um = this.em.get('UndoManager');
+      if (um) {
+        um.remove(this);
+        um.remove(this.components());
+        delete this.__hasUm;
+      }
     },
 
     __onChange(m, opts) {

src/dom_components/model/Components.js

@@ -97,12 +97,10 @@ export default Backbone.Collection.extend({
 
     // Remove stuff registered in DomComponents.handleChanges
     const inner = removed.components();
-    const um = em.get('UndoManager');
     em.stopListening(inner);
     em.stopListening(removed);
     em.stopListening(removed.get('classes'));
-    um.remove(removed);
-    um.remove(inner);
+    removed.__postRemove();
   },
 
   model(attrs, options) {
@@ -252,7 +250,8 @@ export default Backbone.Collection.extend({
       model.setStyle({});
       model.addClass(name);
     }
-    model._initUm();
+
+    model.__postAdd({ recursive: 1 });
     this.__onAddEnd();
   },