How capture event toggle Dropdown?

[ivanferrer]

There is no way to capture the event of when the dropdown is open or closed. This is bad, because I need to customize the top container and pass a class so that the item can come forward between a list of filters.

<ss-multiselect-dropdown
    [options]="items"
    [settings]="multiSelectSettings"
    [texts]="multiSelectText"
    [(ngModel)]="optionsModel"
    (ngModelChange)="emit()"
     no exist ====> (onToggleDropdown)="onOpen()"
    (onLazyLoad)="loadData.emit($event)">
</ss-multiselect-dropdown>

Something similar to this:
onToggleDropdown()