These are only available on et2_container, so app.ts can use eg: this.et2.setWidgetById(...)
getDOMWidgetById(): Same as getWidgetById() it returns et2_DOMWidget instead of et2_widget
getValueWidgetById(): Same as getWidgetById(), but returns et2_valueWidget
getValueById(): Find a widget, get its value
setValueById(): Find a widget, set its value
setDisabledById(): Find a widget, set its disabled state.
