Index: wp-admin/css/ie.css
===================================================================
--- wp-admin/css/ie.css	(revision 7561)
+++ wp-admin/css/ie.css	(working copy)
@@ -139,3 +139,8 @@
 	display: inline-block;
 	padding: 2px 5px;
 }
+
+/* Widgets */
+#sidebar-selector-nav input, #sidebar-selector-nav select {
+	width: expression(Math.min(parseInt(this.offsetWidth), 135 ) + "px");
+}
Index: wp-admin/css/widgets.css
===================================================================
--- wp-admin/css/widgets.css	(revision 7561)
+++ wp-admin/css/widgets.css	(working copy)
@@ -188,3 +188,7 @@
 	width: auto;
 	display: block;
 }
+
+#sidebar-selector-nav input, #sidebar-selector-nav select {
+	max-width: 135px;
+}
Index: wp-admin/widgets.php
===================================================================
--- wp-admin/widgets.php	(revision 7561)
+++ wp-admin/widgets.php	(working copy)
@@ -256,7 +256,7 @@
 	<div id="available-sidebars" class="widget-liquid-right">
 		<h3><?php _e('Current Widgets'); ?></h3>
 
-		<div class="nav">
+		<div class="nav" id="sidebar-selector-nav">
 			<select id="sidebar-selector" name="sidebar">
 <?php foreach ( $wp_registered_sidebars as $sidebar_id => $registered_sidebar ) : $sidebar_id = attribute_escape( $sidebar_id ); ?>
 				<option value='<?php echo $sidebar_id; ?>'<?php selected( $sidebar_id, $sidebar ); ?>><?php echo wp_specialchars( $registered_sidebar['name'] ); ?></option>