Reduce reliance on global variables in the list tables. Allow passing a screen ID to the list tables so that ajax handlers can set the needed screen.

Props nacin
fixes #21871


git-svn-id: http://core.svn.wordpress.org/trunk@21914 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/list-table.php

@@ -14,9 +14,10 @@
  * @since 3.1.0
  *
  * @param string $class The type of the list table, which is the class name.
+ * @param array $args Optional. Arguments to pass to the class. Accepts 'screen'.
  * @return object|bool Object on success, false if the class does not exist.
  */
-function _get_list_table( $class ) {
+function _get_list_table( $class, $args = array() ) {
 	$core_classes = array(
 		//Site Admin
 		'WP_Posts_List_Table' => 'posts',
@@ -39,7 +40,13 @@ function _get_list_table( $class ) {
 	if ( isset( $core_classes[ $class ] ) ) {
 		foreach ( (array) $core_classes[ $class ] as $required )
 			require_once( ABSPATH . 'wp-admin/includes/class-wp-' . $required . '-list-table.php' );
-		return new $class;
+
+		if ( isset( $args['screen'] ) )
+			$args['screen'] = convert_to_screen( $args['screen'] );
+		else
+			$args['screen'] = get_current_screen();
+
+		return new $class( $args );
 	}
 
 	return false;