Index: post.php
===================================================================
--- post.php	(revision 18444)
+++ post.php	(working copy)
@@ -1774,7 +1774,7 @@
 	global $content_width, $post;
 
 	$width = isset($content_width) && 800 > $content_width ? $content_width : 800;
-	$width = $width + 10; // compensate for the padding
+	$width = $width + 22; // compensate for the padding and border
 	$dfw_width = get_user_setting( 'dfw_width', $width );
 	$save = isset($post->post_status) && $post->post_status == 'publish' ? __('Update') : __('Save');
 ?>