Source

File: wp-admin/includes/dashboard.php

function wp_add_dashboard_widget( $widget_id, $widget_name, $callback, $control_callback = null, $callback_args = null ) {
	$screen = get_current_screen();
	global $wp_dashboard_control_callbacks;

	$private_callback_args = array( '__widget_basename' => $widget_name );

	if ( is_null( $callback_args ) ) {
		$callback_args = $private_callback_args;
	} elseif ( is_array( $callback_args ) ) {
		$callback_args = array_merge( $callback_args, $private_callback_args );
	}

	if ( $control_callback && current_user_can( 'edit_dashboard' ) && is_callable( $control_callback ) ) {
		$wp_dashboard_control_callbacks[ $widget_id ] = $control_callback;
		if ( isset( $_GET['edit'] ) && $widget_id == $_GET['edit'] ) {
			list($url)    = explode( '#', add_query_arg( 'edit', false ), 2 );
			$widget_name .= ' <span class="postbox-title-action"><a href="' . esc_url( $url ) . '">' . __( 'Cancel' ) . '</a></span>';
			$callback     = '_wp_dashboard_control_callback';
		} else {
			list($url)    = explode( '#', add_query_arg( 'edit', $widget_id ), 2 );
			$widget_name .= ' <span class="postbox-title-action"><a href="' . esc_url( "$url#$widget_id" ) . '" class="edit-box open-box">' . __( 'Configure' ) . '</a></span>';
		}
	}

	$side_widgets = array( 'dashboard_quick_press', 'dashboard_primary' );

	$location = 'normal';
	if ( in_array( $widget_id, $side_widgets, true ) ) {
		$location = 'side';
	}

	$high_priority_widgets = array( 'dashboard_browser_nag', 'dashboard_php_nag' );

	$priority = 'core';
	if ( in_array( $widget_id, $high_priority_widgets, true ) ) {
		$priority = 'high';
	}

	add_meta_box( $widget_id, $widget_name, $callback, $screen, $location, $priority, $callback_args );
}