Index: wp-admin/includes/class-wp-ms-themes-list-table.php
===================================================================
--- wp-admin/includes/class-wp-ms-themes-list-table.php	(revision 21695)
+++ wp-admin/includes/class-wp-ms-themes-list-table.php	(working copy)
@@ -277,27 +277,28 @@
 			'delete' => ''
 		);
 
-		$theme_key = $theme->get_stylesheet();
+		$theme_key = $stylesheet = $theme->get_stylesheet();
+		$theme_key = urlencode( $theme_key );
 
 		if ( ! $allowed ) {
 			if ( ! $theme->errors() )
-				$actions['enable'] = '<a href="' . esc_url( wp_nonce_url($url . 'action=enable&amp;theme=' . $theme_key . '&amp;paged=' . $page . '&amp;s=' . $s, 'enable-theme_' . $theme_key) ) . '" title="' . esc_attr__('Enable this theme') . '" class="edit">' . ( $this->is_site_themes ? __( 'Enable' ) : __( 'Network Enable' ) ) . '</a>';
+				$actions['enable'] = '<a href="' . esc_url( wp_nonce_url($url . 'action=enable&amp;theme=' . $theme_key . '&amp;paged=' . $page . '&amp;s=' . $s, 'enable-theme_' . $stylesheet) ) . '" title="' . esc_attr__('Enable this theme') . '" class="edit">' . ( $this->is_site_themes ? __( 'Enable' ) : __( 'Network Enable' ) ) . '</a>';
 		} else {
-			$actions['disable'] = '<a href="' . esc_url( wp_nonce_url($url . 'action=disable&amp;theme=' . $theme_key . '&amp;paged=' . $page . '&amp;s=' . $s, 'disable-theme_' . $theme_key) ) . '" title="' . esc_attr__('Disable this theme') . '">' . ( $this->is_site_themes ? __( 'Disable' ) : __( 'Network Disable' ) ) . '</a>';
+			$actions['disable'] = '<a href="' . esc_url( wp_nonce_url($url . 'action=disable&amp;theme=' . $theme_key . '&amp;paged=' . $page . '&amp;s=' . $s, 'disable-theme_' . $stylesheet) ) . '" title="' . esc_attr__('Disable this theme') . '">' . ( $this->is_site_themes ? __( 'Disable' ) : __( 'Network Disable' ) ) . '</a>';
 		}
 
 		if ( current_user_can('edit_themes') )
-			$actions['edit'] = '<a href="' . esc_url('theme-editor.php?theme=' .  $theme_key ) . '" title="' . esc_attr__('Open this theme in the Theme Editor') . '" class="edit">' . __('Edit') . '</a>';
+			$actions['edit'] = '<a href="' . esc_url('theme-editor.php?theme=' .  $theme_key) . '" title="' . esc_attr__('Open this theme in the Theme Editor') . '" class="edit">' . __('Edit') . '</a>';
 
-		if ( ! $allowed && current_user_can( 'delete_themes' ) && ! $this->is_site_themes && $theme_key != get_option( 'stylesheet' ) && $theme_key != get_option( 'template' ) )
+		if ( ! $allowed && current_user_can( 'delete_themes' ) && ! $this->is_site_themes && $stylesheet != get_option( 'stylesheet' ) && $stylesheet != get_option( 'template' ) )
 			$actions['delete'] = '<a href="' . esc_url( wp_nonce_url( 'themes.php?action=delete-selected&amp;checked[]=' . $theme_key . '&amp;theme_status=' . $context . '&amp;paged=' . $page . '&amp;s=' . $s, 'bulk-themes' ) ) . '" title="' . esc_attr__( 'Delete this theme' ) . '" class="delete">' . __( 'Delete' ) . '</a>';
 
-		$actions = apply_filters( 'theme_action_links', array_filter( $actions ), $theme_key, $theme, $context );
-		$actions = apply_filters( "theme_action_links_$theme_key", $actions, $theme_key, $theme, $context );
+		$actions = apply_filters( 'theme_action_links', array_filter( $actions ), $stylesheet, $theme, $context );
+		$actions = apply_filters( "theme_action_links_$stylesheet", $actions, $stylesheet, $theme, $context );
 
 		$class = ! $allowed ? 'inactive' : 'active';
 		$checkbox_id = "checkbox_" . md5( $theme->get('Name') );
-		$checkbox = "<input type='checkbox' name='checked[]' value='" . esc_attr( $theme_key ) . "' id='" . $checkbox_id . "' /><label class='screen-reader-text' for='" . $checkbox_id . "' >" . __('Select') . " " . $theme->display('Name') . "</label>";
+		$checkbox = "<input type='checkbox' name='checked[]' value='" . esc_attr( $stylesheet ) . "' id='" . $checkbox_id . "' /><label class='screen-reader-text' for='" . $checkbox_id . "' >" . __('Select') . " " . $theme->display('Name') . "</label>";
 
 		$id = sanitize_html_class( $theme->get_stylesheet() );
 
@@ -341,7 +342,7 @@
 					if ( $theme->get('ThemeURI') )
 						$theme_meta[] = '<a href="' . $theme->display('ThemeURI') . '" title="' . esc_attr__( 'Visit theme homepage' ) . '">' . __( 'Visit Theme Site' ) . '</a>';
 
-					$theme_meta = apply_filters( 'theme_row_meta', $theme_meta, $theme_key, $theme, $status );
+					$theme_meta = apply_filters( 'theme_row_meta', $theme_meta, $stylesheet, $theme, $status );
 					echo implode( ' | ', $theme_meta );
 
 					echo "</div></td>";
@@ -349,7 +350,7 @@
 
 				default:
 					echo "<td class='$column_name column-$column_name'$style>";
-					do_action( 'manage_themes_custom_column', $column_name, $theme_key, $theme );
+					do_action( 'manage_themes_custom_column', $column_name, $stylesheet, $theme );
 					echo "</td>";
 			}
 		}
@@ -357,8 +358,8 @@
 		echo "</tr>";
 
 		if ( $this->is_site_themes )
-			remove_action( "after_theme_row_$theme_key", 'wp_theme_update_row' );
-		do_action( 'after_theme_row', $theme_key, $theme, $status );
-		do_action( "after_theme_row_$theme_key", $theme_key, $theme, $status );
+			remove_action( "after_theme_row_$stylesheet", 'wp_theme_update_row' );
+		do_action( 'after_theme_row', $stylesheet, $theme, $status );
+		do_action( "after_theme_row_$stylesheet", $stylesheet, $theme, $status );
 	}
 }
Index: wp-admin/includes/class-wp-upgrader.php
===================================================================
--- wp-admin/includes/class-wp-upgrader.php	(revision 21695)
+++ wp-admin/includes/class-wp-upgrader.php	(working copy)
@@ -1500,14 +1500,14 @@
 
 		$preview_link = add_query_arg( array(
 			'preview'    => 1,
-			'template'   => $template,
-			'stylesheet' => $stylesheet,
-		), trailingslashit( get_home_url() ) );
+			'template'   => urlencode( $template ),
+			'stylesheet' => urlencode( $stylesheet ),
+		), trailingslashit( home_url() ) );
 
 		$activate_link = add_query_arg( array(
 			'action'     => 'activate',
-			'template'   => $template,
-			'stylesheet' => $stylesheet,
+			'template'   => urlencode( $template ),
+			'stylesheet' => urlencode( $stylesheet ),
 		), admin_url('themes.php') );
 		$activate_link = wp_nonce_url( $activate_link, 'switch-theme_' . $stylesheet );
 
@@ -1517,7 +1517,7 @@
 		$install_actions['activate'] = '<a href="' . esc_url( $activate_link ) . '" class="activatelink" title="' . esc_attr( sprintf( __('Activate &#8220;%s&#8221;'), $name ) ) . '">' . __('Activate') . '</a>';
 
 		if ( is_network_admin() && current_user_can( 'manage_network_themes' ) )
-			$install_actions['network_enable'] = '<a href="' . esc_url( wp_nonce_url( 'themes.php?action=enable&amp;theme=' . $stylesheet, 'enable-theme_' . $stylesheet ) ) . '" title="' . esc_attr__( 'Enable this theme for all sites in this network' ) . '" target="_parent">' . __( 'Network Enable' ) . '</a>';
+			$install_actions['network_enable'] = '<a href="' . esc_url( wp_nonce_url( 'themes.php?action=enable&amp;theme=' . urlencode( $stylesheet ), 'enable-theme_' . $stylesheet ) ) . '" title="' . esc_attr__( 'Enable this theme for all sites in this network' ) . '" target="_parent">' . __( 'Network Enable' ) . '</a>';
 
 		if ( $this->type == 'web' )
 			$install_actions['themes_page'] = '<a href="' . self_admin_url('theme-install.php') . '" title="' . esc_attr__('Return to Theme Installer') . '" target="_parent">' . __('Return to Theme Installer') . '</a>';
@@ -1564,14 +1564,14 @@
 
 			$preview_link = add_query_arg( array(
 				'preview'    => 1,
-				'template'   => $template,
-				'stylesheet' => $stylesheet,
-			), trailingslashit( get_home_url() ) );
+				'template'   => urlencode( $template ),
+				'stylesheet' => urlencode( $stylesheet ),
+			), trailingslashit( home_url() ) );
 
 			$activate_link = add_query_arg( array(
 				'action'     => 'activate',
-				'template'   => $template,
-				'stylesheet' => $stylesheet,
+				'template'   => urlencode( $template ),
+				'stylesheet' => urlencode( $stylesheet ),
 			), admin_url('themes.php') );
 			$activate_link = wp_nonce_url( $activate_link, 'switch-theme_' . $stylesheet );
 
Index: wp-admin/includes/theme.php
===================================================================
--- wp-admin/includes/theme.php	(revision 21695)
+++ wp-admin/includes/theme.php	(working copy)
@@ -23,7 +23,7 @@
 
 	ob_start();
 	if ( empty( $redirect ) )
-		$redirect = wp_nonce_url('themes.php?action=delete&stylesheet=' . $stylesheet, 'delete-theme_' . $stylesheet);
+		$redirect = wp_nonce_url('themes.php?action=delete&stylesheet=' . urlencode( $stylesheet ), 'delete-theme_' . $stylesheet);
 	if ( false === ($credentials = request_filesystem_credentials($redirect)) ) {
 		$data = ob_get_contents();
 		ob_end_clean();
Index: wp-admin/includes/class-wp-themes-list-table.php
===================================================================
--- wp-admin/includes/class-wp-themes-list-table.php	(revision 21695)
+++ wp-admin/includes/class-wp-themes-list-table.php	(working copy)
@@ -128,7 +128,7 @@
 			$activate_link = wp_nonce_url( "themes.php?action=activate&amp;template=" . urlencode( $template ) . "&amp;stylesheet=" . urlencode( $stylesheet ), 'switch-theme_' . $stylesheet );
 
 			$preview_link = esc_url( add_query_arg(
-				array( 'preview' => 1, 'template' => $template, 'stylesheet' => $stylesheet, 'preview_iframe' => true, 'TB_iframe' => 'true' ),
+				array( 'preview' => 1, 'template' => urlencode( $template ), 'stylesheet' => urlencode( $stylesheet ), 'preview_iframe' => true, 'TB_iframe' => 'true' ),
 				home_url( '/' ) ) );
 
 			$actions = array();
@@ -143,7 +143,7 @@
 					. __( 'Live Preview' ) . '</a>';
 
 			if ( ! is_multisite() && current_user_can( 'delete_themes' ) )
-				$actions['delete'] = '<a class="submitdelete deletion" href="' . wp_nonce_url( "themes.php?action=delete&amp;stylesheet=$stylesheet", 'delete-theme_' . $stylesheet )
+				$actions['delete'] = '<a class="submitdelete deletion" href="' . wp_nonce_url( 'themes.php?action=delete&amp;stylesheet=' . urlencode( $stylesheet ), 'delete-theme_' . $stylesheet )
 					. '" onclick="' . "return confirm( '" . esc_js( sprintf( __( "You are about to delete this theme '%s'\n  'Cancel' to stop, 'OK' to delete." ), $title ) )
 					. "' );" . '">' . __( 'Delete' ) . '</a>';
 
Index: wp-admin/theme-editor.php
===================================================================
--- wp-admin/theme-editor.php	(revision 21695)
+++ wp-admin/theme-editor.php	(working copy)
@@ -46,7 +46,7 @@
 wp_reset_vars( array( 'action', 'error', 'file', 'theme' ) );
 
 if ( $theme )
-	$stylesheet = urldecode( $theme );
+	$stylesheet = $theme;
 else
 	$stylesheet = get_stylesheet();
 
@@ -68,7 +68,7 @@
 	$relative_file = 'style.css';
 	$file = $allowed_files['style.css'];
 } else {
-	$relative_file = urldecode( stripslashes( $file ) );
+	$relative_file = stripslashes( $file );
 	$file = $theme->get_stylesheet_directory() . '/' . $relative_file;
 }