thingsboard/ui-ngx/src/app/shared/components/time/timezone-panel.component.html

<form [formGroup]="timezoneForm" class="mat-content">
  <section class="tb-form-panel">
    <div class="tb-form-panel-title">{{ 'timezone.timezone' | translate }}</div>
    <tb-timezone-select [localBrowserTimezonePlaceholderOnEmpty]="localBrowserTimezonePlaceholderOnEmpty"
                        formControlName="timezone"
                        subscriptSizing="dynamic"
                        appearance="outline"
                        displayLabel="false">
    </tb-timezone-select>
  </section>
</form>
<div fxLayout="row" class="tb-panel-actions" fxLayoutAlign="end center">
  <button type="button"
          mat-button
          [disabled]="(isLoading$ | async)"
          (click)="cancel()">
    {{ 'action.cancel' | translate }}
  </button>
  <button type="button"
          mat-raised-button
          color="primary"
          (click)="update()"
          [disabled]="(isLoading$ | async) || timezoneForm.invalid || !timezoneForm.dirty">
    {{ 'action.apply' | translate }}
  </button>
</div>