sequence, on state tree change improvments

src/mol-model/structure/structure/structure.ts

@@ -513,6 +513,11 @@ namespace Structure {
         return areEquivalent(a.parent || a, b.parent || b)
     }
 
+    /** Check if the structures or their parents are equal */
+    export function areParentsEqual(a: Structure, b: Structure) {
+        return (a.parent || a) === (b.parent || b)
+    }
+
     export class ElementLocationIterator implements Iterator<StructureElement> {
         private current = StructureElement.create();
         private unitIndex = 0;

src/mol-plugin/ui/sequence.tsx

@@ -128,7 +128,9 @@ export class SequenceView extends PluginUIComponent<{ }, SequenceViewState> {
         this.subscribe(this.plugin.state.behavior.currentObject, o => {
             const current = this.plugin.state.dataState.cells.get(o.ref)!;
             this.spine.current = current
-            this.setState(this.getInitialState())
+            if (!Structure.areParentsEqual(this.state.structure, this.getStructure())) {
+                this.setState(this.getInitialState())
+            }
         });
 
         this.subscribe(this.plugin.events.state.object.updated, ({ ref, state }) => {

src/mol-state/tree/spine.ts

@@ -36,15 +36,15 @@ namespace StateTreeSpine {
 
         getRootOfType<T extends StateObject.Ctor>(t: T): StateObject.From<T> | undefined {
             if (!this._current) return void 0;
-            let cell = this._current;
+            let cell = this._current; // check current first
             let ret: StateObjectCell | undefined = void 0;
             while (true) {
-                cell = this.cells.get(cell.transform.parent)!;
                 if (!cell.obj) return void 0;
                 if (cell.obj.type === t.type) {
                     ret = cell;
                 }
                 if (cell.transform.ref === StateTransform.RootRef) return ret ? ret.obj as StateObject.From<T> : void 0;
+                cell = this.cells.get(cell.transform.parent)!; // assign parent for next check
             }
         }