Index: wp-admin/includes/class-wp-ms-themes-list-table.php
===================================================================
--- wp-admin/includes/class-wp-ms-themes-list-table.php	(revision 16180)
+++ wp-admin/includes/class-wp-ms-themes-list-table.php	(working copy)
@@ -9,7 +9,7 @@
 class WP_MS_Themes_List_Table extends WP_List_Table {
 
 	function WP_MS_Themes_List_Table() {
-		global $status, $page;
+		global $status, $page, $current_screen;
 
 		$default_status = get_user_option( 'themes_last_view' );
 		if ( empty( $default_status ) )
@@ -23,7 +23,7 @@
 		$page = $this->get_pagenum();
 
 		parent::WP_List_Table( array(
-			'screen' => 'themes',
+			'screen' => $current_screen,
 			'plural' => 'plugins', // @todo replace with themes and add css
 		) );
 	}
@@ -96,7 +96,7 @@
 			uasort( $this->items, array( &$this, '_order_callback' ) );
 		}
 
-		$themes_per_page = $this->get_items_per_page( 'themes_per_page', 999 );
+		$themes_per_page = $this->get_items_per_page( 'themes_network_per_page' );
 
 		$start = ( $page - 1 ) * $themes_per_page;
 
Index: wp-admin/includes/misc.php
===================================================================
--- wp-admin/includes/misc.php	(revision 16180)
+++ wp-admin/includes/misc.php	(working copy)
@@ -343,13 +343,16 @@
 
 		switch ( $map_option ) {
 			case 'edit_per_page':
-			case 'sites_network_per_page':
 			case 'users_per_page':
-			case 'users_network_per_page':
 			case 'edit_comments_per_page':
 			case 'upload_per_page':
 			case 'edit_tags_per_page':
 			case 'plugins_per_page':
+			// Network admin
+			case 'sites_network_per_page':
+			case 'users_network_per_page':
+			case 'plugins_network_per_page':
+			case 'themes_network_per_page':
 				$value = (int) $value;
 				if ( $value < 1 || $value > 999 )
 					return;
Index: wp-admin/includes/class-wp-plugins-list-table.php
===================================================================
--- wp-admin/includes/class-wp-plugins-list-table.php	(revision 16180)
+++ wp-admin/includes/class-wp-plugins-list-table.php	(working copy)
@@ -9,7 +9,7 @@
 class WP_Plugins_List_Table extends WP_List_Table {
 
 	function WP_Plugins_List_Table() {
-		global $status, $page;
+		global $status, $page, $current_screen;
 
 		$default_status = get_user_option( 'plugins_last_view' );
 		if ( empty( $default_status ) )
@@ -23,7 +23,7 @@
 		$page = $this->get_pagenum();
 
 		parent::WP_List_Table( array(
-			'screen' => 'plugins',
+			'screen' => $current_screen,
 			'plural' => 'plugins',
 		) );
 	}
@@ -43,7 +43,7 @@
 	}
 
 	function prepare_items() {
-		global $status, $plugins, $totals, $page, $orderby, $order, $s;
+		global $status, $plugins, $totals, $page, $orderby, $order, $s, $current_screen;
 
 		wp_reset_vars( array( 'orderby', 'order', 's' ) );
 
@@ -129,7 +129,7 @@
 			uasort( $this->items, array( &$this, '_order_callback' ) );
 		}
 
-		$plugins_per_page = $this->get_items_per_page( 'plugins_per_page', 999 );
+		$plugins_per_page = $this->get_items_per_page( str_replace( '-', '_', "{$current_screen->id}_per_page" ) );
 
 		$start = ( $page - 1 ) * $plugins_per_page;
 
Index: wp-admin/network/themes.php
===================================================================
--- wp-admin/network/themes.php	(revision 16180)
+++ wp-admin/network/themes.php	(working copy)
@@ -66,7 +66,7 @@
 $wp_list_table->prepare_items();
 add_thickbox();
 
-add_screen_option( 'per_page', array('label' => _x( 'Themes', 'themes per page (screen options)' ), 'default' => 999) );
+add_screen_option( 'per_page', array('label' => _x( 'Themes', 'themes per page (screen options)' )) );
 
 add_contextual_help($current_screen, 
 	'<p>' . __('This screen enables and disables the inclusion of themes available to choose in the Appearance menu for each site. It does not activate or deactivate which theme a site is currently using.') . '</p>' . 
Index: wp-admin/plugins.php
===================================================================
--- wp-admin/plugins.php	(revision 16180)
+++ wp-admin/plugins.php	(working copy)
@@ -296,7 +296,7 @@
 wp_enqueue_script('plugin-install');
 add_thickbox();
 
-add_screen_option( 'per_page', array('label' => _x( 'Plugins', 'plugins per page (screen options)' ), 'default' => 999) );
+add_screen_option( 'per_page', array('label' => _x( 'Plugins', 'plugins per page (screen options)' )) );
 
 add_contextual_help($current_screen,
 	'<p>' . __('Plugins extend and expand the functionality of WordPress. Once a plugin is installed, you may activate it or deactivate it here.') . '</p>' .