title: UI is not updated by updating observable from the custom binding method update
body: <p>I'm working on a knockout application in which there is a drop-down for selecting a day of a month, it's values changes as per the month selection (ex: May- 1 to 31, Nov- 1 to 30), I successfully rendered UI, but my problem is the selected value (<code>this.dayValue</code>) is not showing as updated on UI when I tried to update from the update of the knockout binding handler. I've given the sample code below, please let me know. I guess it is a problem of rebinding even though I'm not sure. please help. Thanks in advance.</p>
  <p><strong>HTML:</strong></p>
  <pre><code>&lt;script type=&quot;text/html&quot; id=&quot;person-template&quot;&gt;
      &lt;select data-bind=&quot;options: months, value: monthValue, event:{change: $data.noOfDays}&gt;&lt;/select&gt;
      **&lt;select data-bind=&quot;options: days, value: dayValue, event:{change: $data.dateModifiy}&gt;&lt;/select&gt;**
      &lt;select data-bind=&quot;options: years, value: yearValue, event:{change: $data.dateModifiy}&gt;&lt;/select&gt;
  &lt;/script&gt;
  </code></pre>
  <p><strong>Typescript:</strong></p>
  <pre><code>export class MyView{
    private dayValue: Observable&lt;string&gt;;
     constructor(opt: Iclass){
       this.dayValue = opt.current().getDate().toString();
    }
    private noOfDays(): void {
      let temp: string[] = [];
      let month: number = this.months().indexOf(this.monthValue());
      let noOfDays: number = new Date(this.yearValue(), month + 1, 0).getDate();
      for (let i: number = 1; i &lt;= noOfDays; i++) {
        temp.push(i.toString());
      }
      this.days(temp);
    }
  }
  
  ko.bindingHandlers.MyDate = {
      init(element: HTMLElement, valueAccessor: any, allBindingsAccessor: any, viewModel: any, bindingContext: any): any {
      let options: Iclass = ko.utils.unwrapObservable(valueAccessor()) || {};
      let myView: Myview = new MyView(options);
  
      ko.cleanNode(element);
      ko.applyBindingsToNode(element, {
          template: {
              name: &quot;person-template&quot;,
              data: myView
          }
      });
  
      return { controlsDescendantBindings: true };
  },
  
  update(element: HTMLElement, valueAccessor: any, allBindingsAccessor: any, viewModel: any, bindingContext: any): any {
      let options: Iclass = ko.utils.unwrapObservable(valueAccessor()) || {};
      let myView: Myview = new MyView(options);
  }
  </code></pre>
  <p><strong>Sample Code:</strong></p>
  <pre><code>&lt;div data-bind=&quot;MyDate:{ name: 'sample', current: newDate}&quot;&gt;&lt;/div&gt;
  </code></pre>