public function widget( $args, $instance ) {
		echo $args; //This is a HTML content//
		echo '<div id="wpf-widget-online-users" class="wpforo-widget-wrap">';
		if ( ! empty( $instance ) ) {
			echo $args . apply_filters( 'widget_title', $instance ). $args;
		}
        $groupids = ( !empty($instance) ? array_filter( wpforo_parse_args( json_decode($instance, true) ) ) : WPF()->usergroup->get_visible_usergroup_ids() );
		// widget content from front end
		$online_members = WPF()->member->get_online_members($instance, $groupids);
		echo '<div class="wpforo-widget-content">';
		if(!empty($online_members)){
			echo '<ul>
					 <li>
						<div class="wpforo-list-item">';
			foreach( $online_members as $member ){
				if( $instance ): ?>
						<a href="<?php echo esc_url(WPF()->member->get_profile_url( $member )) ?>" class="onlineavatar">
							<?php echo WPF()->member->get_avatar( $member, 'style="width:95%;" class="avatar" title="'.esc_attr($member).'"'); ?>
						</a>
					<?php else: ?>
						<a href="<?php echo esc_url(WPF()->member->get_profile_url( $member )) ?>" class="onlineuser"><?php echo esc_html($member) ?></a>
					<?php endif; ?>
				<?php
			}
			echo '<div class="wpf-clear"></div>
							</div>
						</li>
					</ul>';
			// nando4>> bug in widget - move div that was here below
		}
		else{
			echo '<p class="wpf-widget-note">&nbsp;'.wpforo_phrase('No online members at the moment', false).'</p>';
		}
		echo '</div>';
		echo '</div>';
		echo $args;//This is a HTML content//
	}

Even if i set with no selections the read only option on usergroups and on forum access the widget show the member online of my private forum. There is a bug ?

Thanks

https://wpforo.com/docs/root/getting-started/forum-sidebar-and-widgets/wpforo-widgets/

In any case if you want to remove the grey square boarder just please use this CSS code:

#wpf-widget-online-users .wpforo-widget-content a.onlineavatar {border: none!important;}