gistfile1.php

add_filter( 'tribe-events-bar-filters',  'setup_my_field_in_bar', 1, 1 );

public function setup_my_field_in_bar( $filters ) {
  $filters['tribe-bar-my-field'] = array( 'name'    => 'tribe-bar-my-field',
	                                        'caption' => 'My Field',
	                                        'html'    => '<input type="text" name="tribe-bar-my-field" id="tribe-bar-my-field">' );

	return $filters;
}