bbp_edit_user_display_name()

function bbp_edit_user_display_name() {
	$bbp            = bbpress();
	$public_display = array();
	$public_display['display_username'] = $bbp->displayed_user->user_login;

	if ( !empty( $bbp->displayed_user->nickname ) )
		$public_display['display_nickname']  = $bbp->displayed_user->nickname;

	if ( !empty( $bbp->displayed_user->first_name ) )
		$public_display['display_firstname'] = $bbp->displayed_user->first_name;

	if ( !empty( $bbp->displayed_user->last_name ) )
		$public_display['display_lastname']  = $bbp->displayed_user->last_name;

	if ( !empty( $bbp->displayed_user->first_name ) && !empty( $bbp->displayed_user->last_name ) ) {
		$public_display['display_firstlast'] = $bbp->displayed_user->first_name . ' ' . $bbp->displayed_user->last_name;
		$public_display['display_lastfirst'] = $bbp->displayed_user->last_name  . ' ' . $bbp->displayed_user->first_name;
	}

	if ( !in_array( $bbp->displayed_user->display_name, $public_display ) ) // Only add this if it isn't duplicated elsewhere
		$public_display = array( 'display_displayname' => $bbp->displayed_user->display_name ) + $public_display;

	$public_display = array_map( 'trim', $public_display );
	$public_display = array_unique( $public_display ); ?>

	<select name="display_name" id="display_name">

	<?php foreach ( $public_display as $id => $item ) : ?>

		<option id="<?php echo $id; ?>" value="<?php echo esc_attr( $item ); ?>"<?php selected( $bbp->displayed_user->display_name, $item ); ?>><?php echo $item; ?></option>

	<?php endforeach; ?>

	</select>

<?php
}