Index: src/wp-admin/plugin-editor.php
===================================================================
--- src/wp-admin/plugin-editor.php	(revision 29798)
+++ src/wp-admin/plugin-editor.php	(working copy)
@@ -197,12 +198,29 @@
 		<strong><label for="plugin"><?php _e('Select plugin to edit:'); ?> </label></strong>
 		<select name="plugin" id="plugin">
 <?php
+	if ( strpos( $plugin, '/'  ) !== false ) {
+		$plugin_path = explode( '/', $plugin );
+		$plugin_root_path = $plugin_path[0];
+	} else {
+		$plugin_root_path = '';
+	}
+
 	foreach ( $plugins as $plugin_key => $a_plugin ) {
 		$plugin_name = $a_plugin['Name'];
-		if ( $plugin_key == $plugin )
-			$selected = " selected='selected'";
-		else
-			$selected = '';
+		if ( $plugin_root_path !== '' ) {
+			if ( strpos( $plugin_key, trailingslashit( $plugin_root_path ) ) === 0 ) {
+				$selected = " selected='selected'";
+			} else {
+				$selected = '';
+			}
+		} else {
+			if ( $plugin_key == $plugin ) {
+				$selected = " selected='selected'";
+			} else {
+				$selected = '';
+			}
+		}
+
 		$plugin_name = esc_attr($plugin_name);
 		$plugin_key = esc_attr($plugin_key);
 		echo "\n\t<option value=\"$plugin_key\" $selected>$plugin_name</option>";