diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index 8829a7fa83..588bc50895 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -933,10 +933,10 @@ function postbox_classes( $id, $page ) {
  *
  * @since unknown
  *
- * @param unknown_type $id
- * @param unknown_type $title
- * @param unknown_type $name
- * @return unknown
+ * @param int|object $id    Post ID or post object. 
+ * @param string $title (optional) Title 
+ * @param string $name (optional) Name 
+ * @return array With two entries of type string 
  */
 function get_sample_permalink($id, $title = null, $name = null) {
 	$post = &get_post($id);
@@ -951,7 +951,7 @@ function get_sample_permalink($id, $title = null, $name = null) {
 	// drafts, so we will fake, that our post is published
 	if (in_array($post->post_status, array('draft', 'pending'))) {
 		$post->post_status = 'publish';
-		$post->post_name = sanitize_title($post->post_name? $post->post_name : $post->post_title, $post->ID);
+		$post->post_name = sanitize_title($post->post_name ? $post->post_name : $post->post_title, $post->ID);
 	}
 
 	$post->post_name = wp_unique_post_slug($post->post_name, $post->ID, $post->post_status, $post->post_type, $post->post_parent);
@@ -959,7 +959,7 @@ function get_sample_permalink($id, $title = null, $name = null) {
 	// If the user wants to set a new name -- override the current one
 	// Note: if empty name is supplied -- use the title instead, see #6072
 	if (!is_null($name)) {
-		$post->post_name = sanitize_title($name? $name : $title, $post->ID);
+		$post->post_name = sanitize_title($name ? $name : $title, $post->ID);
 	}
 
 	$post->filter = 'sample';
@@ -987,14 +987,16 @@ function get_sample_permalink($id, $title = null, $name = null) {
 }
 
 /**
- * {@internal Missing Short Description}}
+ * sample permalink html
  *
+ * intended to be used for the inplace editor of the permalink post slug on in the post (and page?) editor.
+ * 
  * @since unknown
  *
- * @param unknown_type $id
- * @param unknown_type $new_title
- * @param unknown_type $new_slug
- * @return unknown
+ * @param int|object $id Post ID or post object. 
+ * @param string $new_title (optional) New title  
+ * @param string $new_slug (optional) New slug 
+ * @return string intended to be used for the inplace editor of the permalink post slug on in the post (and page?) editor. 
  */
 function get_sample_permalink_html( $id, $new_title = null, $new_slug = null ) {
 	$post = &get_post($id);
diff --git a/wp-admin/includes/widgets.php b/wp-admin/includes/widgets.php
index d452b56092..ac3cd05c25 100644
--- a/wp-admin/includes/widgets.php
+++ b/wp-admin/includes/widgets.php
@@ -190,8 +190,8 @@ function wp_widget_control( $sidebar_args ) {
 	</div>
 	<input type="hidden" name="widget-id" class="widget-id" value="<?php echo esc_attr($id_format); ?>" />
 	<input type="hidden" name="id_base" class="id_base" value="<?php echo esc_attr($id_base); ?>" />
-	<input type="hidden" name="widget-width" class="widget-width" value="<?php echo esc_attr($control['width']); ?>" />
-	<input type="hidden" name="widget-height" class="widget-height" value="<?php echo esc_attr($control['height']); ?>" />
+	<input type="hidden" name="widget-width" class="widget-width" value="<?php if (isset( $control['width'] )) echo esc_attr($control['width']); ?>" />
+	<input type="hidden" name="widget-height" class="widget-height" value="<?php if (isset( $control['height'] )) echo esc_attr($control['height']); ?>" />
 	<input type="hidden" name="widget_number" class="widget_number" value="<?php echo esc_attr($widget_number); ?>" />
 	<input type="hidden" name="multi_number" class="multi_number" value="<?php echo esc_attr($multi_number); ?>" />
 	<input type="hidden" name="add_new" class="add_new" value="<?php echo esc_attr($add_new); ?>" />
diff --git a/wp-admin/upload.php b/wp-admin/upload.php
index bfdf76e4d1..8853bb715d 100644
--- a/wp-admin/upload.php
+++ b/wp-admin/upload.php
@@ -308,7 +308,7 @@ if ( !is_singular() && !isset($_GET['detached']) && !$is_trash ) {
 
 	if ( $month_count && !( 1 == $month_count && 0 == $arc_result[0]->mmonth ) ) : ?>
 <select name='m'>
-<option<?php selected( @$_GET['m'], 0 ); ?> value='0'><?php _e('Show all dates'); ?></option>
+<option value='0'><?php _e('Show all dates'); ?></option>
 <?php
 foreach ($arc_result as $arc_row) {
 	if ( $arc_row->yyear == 0 )
diff --git a/wp-comments-post.php b/wp-comments-post.php
index 03d52bc04e..8fa0548991 100644
--- a/wp-comments-post.php
+++ b/wp-comments-post.php
@@ -17,7 +17,7 @@ require( dirname(__FILE__) . '/wp-load.php' );
 
 nocache_headers();
 
-$comment_post_ID = (int) $_POST['comment_post_ID'];
+$comment_post_ID = isset($_POST['comment_post_ID']) ? (int) $_POST['comment_post_ID'] : 0;
 
 $status = $wpdb->get_row( $wpdb->prepare("SELECT post_status, comment_status FROM $wpdb->posts WHERE ID = %d", $comment_post_ID) );
 
diff --git a/wp-includes/author-template.php b/wp-includes/author-template.php
index 84fb6f5568..51ff8a97ae 100644
--- a/wp-includes/author-template.php
+++ b/wp-includes/author-template.php
@@ -22,7 +22,7 @@
  */
 function get_the_author($deprecated = '') {
 	global $authordata;
-	return apply_filters('the_author', $authordata->display_name);
+	return apply_filters('the_author', is_object($authordata) ? $authordata->display_name : null);
 }
 
 /**
diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index d1623d2bd9..42fa875629 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -1137,7 +1137,7 @@ function wp_new_comment( $commentdata ) {
 	else
 		$commentdata['user_id'] = $commentdata['user_ID'] = (int) $commentdata['user_id'];
 
-	$commentdata['comment_parent'] = absint($commentdata['comment_parent']);
+	$commentdata['comment_parent'] = isset($commentdata['comment_parent']) ? absint($commentdata['comment_parent']) : 0;
 	$parent_status = ( 0 < $commentdata['comment_parent'] ) ? wp_get_comment_status($commentdata['comment_parent']) : '';
 	$commentdata['comment_parent'] = ( 'approved' == $parent_status || 'unapproved' == $parent_status ) ? $commentdata['comment_parent'] : 0;
 
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 80bf43a26e..3110ba4c63 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -1941,6 +1941,8 @@ function check_and_publish_future_post($post_id) {
 /**
  * Given the desired slug and some post details computes a unique slug for the post.
  *
+ * @global wpdb $wpdb 
+ * @global WP_Rewrite $wp_rewrite 
  * @param string $slug the desired slug (post_name)
  * @param integer $post_ID
  * @param string $post_status no uniqueness checks are made if the post is still draft or pending
@@ -1953,13 +1955,18 @@ function wp_unique_post_slug($slug, $post_ID, $post_status, $post_type, $post_pa
 		return $slug;
 
 	global $wpdb, $wp_rewrite;
+
+	$feeds = $wp_rewrite->feeds;
+	if ( !is_array($feeds) )
+		$feeds = array();
+
 	$hierarchical_post_types = apply_filters('hierarchical_post_types', array('page'));
 	if ( 'attachment' == $post_type ) {
 		// Attachment slugs must be unique across all types.
 		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND ID != %d LIMIT 1";
 		$post_name_check = $wpdb->get_var($wpdb->prepare($check_sql, $slug, $post_ID));
 
-		if ( $post_name_check || in_array($slug, $wp_rewrite->feeds) ) {
+		if ( $post_name_check || in_array($slug, $feeds) ) {
 			$suffix = 2;
 			do {
 				$alt_post_name = substr($slug, 0, 200-(strlen($suffix)+1)). "-$suffix";
@@ -1974,7 +1981,7 @@ function wp_unique_post_slug($slug, $post_ID, $post_status, $post_type, $post_pa
 		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( '" . implode("', '", esc_sql($hierarchical_post_types)) . "' ) AND ID != %d AND post_parent = %d LIMIT 1";
 		$post_name_check = $wpdb->get_var($wpdb->prepare($check_sql, $slug, $post_ID, $post_parent));
 
-		if ( $post_name_check || in_array($slug, $wp_rewrite->feeds) ) {
+		if ( $post_name_check || in_array($slug, $feeds) ) {
 			$suffix = 2;
 			do {
 				$alt_post_name = substr($slug, 0, 200-(strlen($suffix)+1)). "-$suffix";
diff --git a/wp-includes/vars.php b/wp-includes/vars.php
index b66b31311b..ec2be5e445 100644
--- a/wp-includes/vars.php
+++ b/wp-includes/vars.php
@@ -37,22 +37,24 @@ if ( is_admin() ) {
 // Simple browser detection
 $is_lynx = $is_gecko = $is_winIE = $is_macIE = $is_opera = $is_NS4 = $is_safari = $is_chrome = $is_iphone = false;
 
-if (strpos($_SERVER['HTTP_USER_AGENT'], 'Lynx') !== false) {
-	$is_lynx = true;
-} elseif ( strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'chrome') !== false ) {
-	$is_chrome = true;
-} elseif ( strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'safari') !== false ) {
-	$is_safari = true;
-} elseif (strpos($_SERVER['HTTP_USER_AGENT'], 'Gecko') !== false) {
-	$is_gecko = true;
-} elseif (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Win') !== false) {
-	$is_winIE = true;
-} elseif (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Mac') !== false) {
-	$is_macIE = true;
-} elseif (strpos($_SERVER['HTTP_USER_AGENT'], 'Opera') !== false) {
-	$is_opera = true;
-} elseif (strpos($_SERVER['HTTP_USER_AGENT'], 'Nav') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Mozilla/4.') !== false) {
-	$is_NS4 = true;
+if ( isset($_SERVER['HTTP_USER_AGENT']) ) {
+	if ( strpos($_SERVER['HTTP_USER_AGENT'], 'Lynx') !== false ) {
+		$is_lynx = true;
+	} elseif ( strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'chrome') !== false ) {
+		$is_chrome = true;
+	} elseif ( strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'safari') !== false ) {
+		$is_safari = true;
+	} elseif ( strpos($_SERVER['HTTP_USER_AGENT'], 'Gecko') !== false ) {
+		$is_gecko = true;
+	} elseif ( strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Win') !== false ) {
+		$is_winIE = true;
+	} elseif ( strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Mac') !== false ) {
+		$is_macIE = true;
+	} elseif ( strpos($_SERVER['HTTP_USER_AGENT'], 'Opera') !== false ) {
+		$is_opera = true;
+	} elseif ( strpos($_SERVER['HTTP_USER_AGENT'], 'Nav') !== false && strpos($_SERVER['HTTP_USER_AGENT'], 'Mozilla/4.') !== false ) {
+		$is_NS4 = true;
+	}
 }
 
 if ( $is_safari && strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'mobile') !== false )
diff --git a/wp-trackback.php b/wp-trackback.php
index 2c45d472c7..864da720c3 100644
--- a/wp-trackback.php
+++ b/wp-trackback.php
@@ -36,18 +36,18 @@ function trackback_response($error = 0, $error_message = '') {
 // trackback is done by a POST
 $request_array = 'HTTP_POST_VARS';
 
-if ( !$_GET['tb_id'] ) {
+if ( !isset($_GET['tb_id']) || !$_GET['tb_id'] ) {
 	$tb_id = explode('/', $_SERVER['REQUEST_URI']);
 	$tb_id = intval( $tb_id[ count($tb_id) - 1 ] );
 }
 
-$tb_url  = $_POST['url'];
-$charset = $_POST['charset'];
+$tb_url  = isset($_POST['url'])     ? $_POST['url']     : '';
+$charset = isset($_POST['charset']) ? $_POST['charset'] : '';
 
 // These three are stripslashed here so that they can be properly escaped after mb_convert_encoding()
-$title     = stripslashes($_POST['title']);
-$excerpt   = stripslashes($_POST['excerpt']);
-$blog_name = stripslashes($_POST['blog_name']);
+$title     = isset($_POST['title'])     ? stripslashes($_POST['title'])      : '';
+$excerpt   = isset($_POST['excerpt'])   ? stripslashes($_POST['excerpt'])    : '';
+$blog_name = isset($_POST['blog_name']) ? stripslashes($_POST['blog_name'])  : '';
 
 if ($charset)
 	$charset = str_replace( array(',', ' '), '', strtoupper( trim($charset) ) );
@@ -72,7 +72,7 @@ $blog_name = $wpdb->escape($blog_name);
 if ( is_single() || is_page() )
 	$tb_id = $posts[0]->ID;
 
-if ( !intval( $tb_id ) )
+if ( !isset($tb_id) || !intval( $tb_id ) )
 	trackback_response(1, 'I really need an ID for this to work.');
 
 if (empty($title) && empty($tb_url) && empty($blog_name)) {