underscores are allowed in URLs

better-twitter-widget.php

@@ -424,7 +424,7 @@ class better_twitter_widget extends WP_Widget {
                 $search = array();
                 $search[0] = '/([\s>\-\.])#([[:alnum:]öäü]+)/i';  // text #hash text; >#hash text
                 $search[1] = '/([\s>\-\.])@([[:alnum:]_]+)/';  // @user
-                $search[2] = '/([\s>\-\.])(https?:[\/[:alnum:]\.\?\&#\=\%\+\-]+)/';  // http...
+                $search[2] = '/([\s>\-\.])(https?:[\/[:alnum:]\.\?\&#\=\%\+\-\_]+)/';  // http...
 
                 $replace = array();
                 $replace[0] = '$1<a target="_blank" href="http://twitter.com/search?q=%23$2">#$2</a>';