Fix issue 169

yasnippet.el

@@ -826,7 +826,7 @@ Key bindings:
 
 `yas/minor-mode-on' is usually called by `yas/global-mode' so
 this effectively lets you define exceptions to the \"global\"
-behaviour.")
+behaviour. Can also be a function of zero arguments.")
 (make-variable-buffer-local 'yas/dont-activate)
 
 (defun yas/minor-mode-on ()
@@ -837,7 +837,7 @@ Do this unless `yas/dont-activate' is t "
   (unless (or (minibufferp)
               (and (functionp yas/dont-activate)
                    (funcall yas/dont-activate))
-              (and (not (functionp yas/dont-activate))
+              (and (boundp yas/dont-activate)
                    yas/dont-activate))
     ;; Load all snippets definitions unless we still don't have a
     ;; root-directory or some snippets have already been loaded.
@@ -4237,9 +4237,16 @@ Remaining args as in `yas/expand-snippet'."
 
 
 ;;; Some hacks:
-;; `locate-dominating-file' is added for compatibility in emacs < 23
-(unless (or (eq emacs-major-version 23)
-            (fboundp 'locate-dominating-file))
+;;; 
+;; `locate-dominating-file' 
+;; `region-active-p'
+;; 
+;; added for compatibility in emacs < 23
+(unless (>= emacs-major-version 23)
+  (unless (fboundp 'region-active-p)
+    (defun region-active-p ()  (and transient-mark-mode mark-active)))
+
+  (unless (fboundp 'locate-dominating-file)
     (defvar locate-dominating-stop-dir-regexp
       "\\`\\(?:[\\/][\\/][^\\/]+[\\/]\\|/\\(?:net\\|afs\\|\\.\\.\\.\\)/\\)\\'"
       "Regexp of directory names which stop the search in `locate-dominating-file'.
@@ -4287,7 +4294,7 @@ and return the directory.  Return nil if not found."
                                    file (file-name-directory
                                          (directory-file-name file))))
                  (setq file nil))))
-      root)))
+        root))))
 
 ;; `c-neutralize-syntax-in-CPP` sometimes fires "End of Buffer" error
 ;; (when it execute forward-char) and interrupt the after change