Index: wp-admin/admin-ajax.php
===================================================================
--- wp-admin/admin-ajax.php	(revision 21789)
+++ wp-admin/admin-ajax.php	(working copy)
@@ -49,7 +49,7 @@
 	'hidden-columns', 'update-welcome-panel', 'menu-get-metabox', 'wp-link-ajax',
 	'menu-locations-save', 'menu-quick-search', 'meta-box-order', 'get-permalink',
 	'sample-permalink', 'inline-save', 'inline-save-tax', 'find_posts', 'widgets-order',
-	'save-widget', 'set-post-thumbnail', 'date_format', 'time_format', 'wp-fullscreen-save-post',
+	'save-widget', 'delete-inactive-widgets', 'set-post-thumbnail', 'date_format', 'time_format', 'wp-fullscreen-save-post',
 	'wp-remove-post-lock', 'dismiss-wp-pointer', 'upload-attachment', 'get-attachment', 'query-attachments',
 );
 
Index: wp-admin/includes/ajax-actions.php
===================================================================
--- wp-admin/includes/ajax-actions.php	(revision 21789)
+++ wp-admin/includes/ajax-actions.php	(working copy)
@@ -1607,6 +1607,25 @@
 	wp_die();
 }
 
+function wp_ajax_delete_inactive_widgets() {
+	check_ajax_referer( 'remove-inactive-widgets', 'removeinactivewidgets' );
+
+	if ( !current_user_can('edit_theme_options') )
+		wp_die( -1 );
+
+	unset( $_POST['removeinactivewidgets'], $_POST['action'] );
+
+	do_action('load-widgets.php');
+	do_action('widgets.php');
+	do_action('sidebar_admin_setup');
+
+	$sidebars_widgets = wp_get_sidebars_widgets();
+	$sidebars_widgets['wp_inactive_widgets'] = array();
+	wp_set_sidebars_widgets( $sidebars_widgets );
+
+	wp_die();
+}
+
 function wp_ajax_upload_attachment() {
 	check_ajax_referer( 'media-form' );
 
Index: wp-admin/js/widgets.js
===================================================================
--- wp-admin/js/widgets.js	(revision 21789)
+++ wp-admin/js/widgets.js	(working copy)
@@ -63,6 +63,9 @@
 			} else if ( target.hasClass('widget-control-close') ) {
 				wpWidgets.close( target.closest('div.widget') );
 				e.preventDefault();
+			} else if ( target.attr( 'id' ) == 'inactive-widgets-control-remove' ) {
+				wpWidgets.removeInactiveWidgets();
+				e.preventDefault();
 			}
 		});
 
@@ -247,6 +250,24 @@
 		});
 	},
 
+	removeInactiveWidgets : function() {
+		var sb = $( '.inactive-sidebar' ), data, a;
+
+		$( '.ajax-feedback', sb ).css( 'visibility', 'visible' );
+
+		a = {
+			action : 'delete-inactive-widgets',
+			removeinactivewidgets : $( '#_wpnonce_remove_inactive_widgets' ).val()
+		};
+
+		data = $.param( a );
+
+		$.post( ajaxurl, data, function() {
+			$( '.ajax-feedback' ).css( 'visibility', 'hidden' );
+			$( '#wp_inactive_widgets .widget' ).remove();
+		} );
+	},
+
 	appendTitle : function(widget) {
 		var title = $('input[id*="-title"]', widget).val() || '';
 
Index: wp-admin/css/wp-admin.css
===================================================================
--- wp-admin/css/wp-admin.css	(revision 21789)
+++ wp-admin/css/wp-admin.css	(working copy)
@@ -7928,6 +7928,11 @@
 	margin: 5px 15px 10px;
 }
 
+.inactive .remove-inactive-widgets {
+	clear: both;
+	margin: 0 15px 15px;
+}
+
 #available-widgets p.description {
 	margin: 0 12px 12px;
 }
Index: wp-admin/widgets.php
===================================================================
--- wp-admin/widgets.php	(revision 21789)
+++ wp-admin/widgets.php	(working copy)
@@ -191,6 +191,19 @@
 	exit;
 }
 
+// We're removing inactive widgets without js
+if ( isset( $_POST['removeinactivewidgets'] ) ) {
+	check_admin_referer( 'remove-inactive-widgets', '_wpnonce_remove_inactive_widgets' );
+
+	if ( $_POST['removeinactivewidgets'] ) {
+		$sidebars_widgets['wp_inactive_widgets'] = array();
+		wp_set_sidebars_widgets( $sidebars_widgets );
+	}
+
+	wp_redirect( admin_url( 'widgets.php?message=0' ) );
+	exit;
+}
+
 // Output the widget form without js
 if ( isset($_GET['editwidget']) && $_GET['editwidget'] ) {
 	$widget_id = $_GET['editwidget'];
@@ -365,7 +378,13 @@
 			</div>
 			<div class="widget-holder inactive">
 				<?php wp_list_widget_controls( $registered_sidebar['id'] ); ?>
-				<div class="clear"></div>
+				<div class="remove-inactive-widgets">
+					<form action="" method="post">
+						<?php submit_button( __( 'Clear Inactive Widgets' ), 'delete', 'removeinactivewidgets', false, array( 'id' => 'inactive-widgets-control-remove' ) ); ?>
+						<span class="description"><?php _e( 'This will clear all items from the inactive widgets list. You will not be able to restore any customizations.' ); ?></span>
+						<?php wp_nonce_field( 'remove-inactive-widgets', '_wpnonce_remove_inactive_widgets' ); ?>
+					</form>
+				</div>
 			</div>
 		</div>
 <?php