Index: wp-admin/includes/class-wp-upgrader.php
===================================================================
--- wp-admin/includes/class-wp-upgrader.php	(revision 14088)
+++ wp-admin/includes/class-wp-upgrader.php	(working copy)
@@ -1055,7 +1055,7 @@
 	function add_strings() {
 		$this->upgrader->strings['skin_update_failed_error'] = __('An error occured while updating %1$s: <strong>%2$s</strong>.');
 		$this->upgrader->strings['skin_update_failed'] = __('The update of %1$s failed.');
-		$this->upgrader->strings['skin_update_successful'] = __('%1$s updated successfully. <a onclick="%2$s" href="#">See Details</a>.');
+		$this->upgrader->strings['skin_update_successful'] = __('%1$s updated successfully. <a onclick="%2$s" href="#"><span>Show Details</span><span class="hidden">Hide Details</span></a>.');
 	}
 
 	function feedback($string) {
@@ -1116,7 +1116,7 @@
 			echo '<script type="text/javascript">jQuery(\'#progress-' . esc_js($this->upgrader->update_current) . '\').show();</script>';
 		}
 		if ( !empty($this->result) && !is_wp_error($this->result) ) {
-			echo '<div class="updated"><p>' . sprintf($this->upgrader->strings['skin_update_successful'], $title, 'jQuery(\'#progress-' . esc_js($this->upgrader->update_current) . '\').toggle(); return false;') . '</p></div>';
+			echo '<div class="updated"><p>' . sprintf($this->upgrader->strings['skin_update_successful'], $title, 'jQuery(\'#progress-' . esc_js($this->upgrader->update_current) . '\').toggle();jQuery(\'span\', this).toggle(); return false;') . '</p></div>';
 		}
 		$this->reset();
 		$this->flush_output();