Fix global dynamic variables prefixes in org-beamer.el.

Thanks to Martyn Jago for the patch.

lisp/org-beamer.el

@@ -235,7 +235,7 @@ in org-export-latex-classes."
 	 (envs (append org-beamer-environments-extra
 		       org-beamer-environments-default))
 	 (props (org-get-text-property-any 0 'org-props text))
-	 (in "") (out "") option action defaction environment extra
+	 (in "") (out "") org-beamer-option org-beamer-action org-beamer-defaction org-beamer-environment org-beamer-extra
 	 columns-option column-option
 	 env have-text ass tmp)
     (if (= frame-level 0) (setq frame-level nil))
@@ -266,10 +266,10 @@ in org-export-latex-classes."
 
       (setq in (org-fill-template
 		"\\begin{frame}%a%A%o%T%S%x"
-		(list (cons "a" (or action ""))
-		      (cons "A" (or defaction ""))
-		      (cons "o" (or option org-beamer-frame-default-options ""))
-		      (cons "x" (if extra (concat "\n" extra) ""))
+		(list (cons "a" (or org-beamer-action ""))
+		      (cons "A" (or org-beamer-defaction ""))
+		      (cons "o" (or org-beamer-option org-beamer-frame-default-options ""))
+		      (cons "x" (if org-beamer-extra (concat "\n" org-beamer-extra) ""))
 		      (cons "h" "%s")
 		      (cons "T" (if (string-match "\\S-" text)
 				    "\n\\frametitle{%s}" ""))
@@ -294,10 +294,10 @@ in org-export-latex-classes."
       (setq have-text (string-match "\\S-" text))
       (setq in (org-fill-template
 		(nth 2 ass)
-		(list (cons "a" (or action ""))
-		      (cons "A" (or defaction ""))
-		      (cons "o" (or option ""))
-		      (cons "x" (if extra (concat "\n" extra) ""))
+		(list (cons "a" (or org-beamer-action ""))
+		      (cons "A" (or org-beamer-defaction ""))
+		      (cons "o" (or org-beamer-option ""))
+		      (cons "x" (if org-beamer-extra (concat "\n" org-beamer-extra) ""))
 		      (cons "h" "%s")
 		      (cons "H" (if have-text (concat "{" text "}") ""))
 		      (cons "U" (if have-text (concat "[" text "]") ""))))
@@ -321,31 +321,31 @@ in org-export-latex-classes."
       (cons text (cdr (assoc level default))))
      (t nil))))
 
-(defvar extra)
-(defvar option)
-(defvar action)
-(defvar defaction)
-(defvar environment)
+(defvar org-beamer-extra)
+(defvar org-beamer-option)
+(defvar org-beamer-action)
+(defvar org-beamer-defaction)
+(defvar org-beamer-environment)
 (defun org-beamer-get-special (props)
   "Extract an option, action, and default action string from text.
-The variables option, action, defaction, extra are all scoped into
-this function dynamically."
+The variables org-beamer-option, org-beamer-action, org-beamer-defaction,
+org-beamer-extra are all scoped into this function dynamically."
   (let (tmp)
-    (setq environment (org-beamer-assoc-not-empty "BEAMER_env" props))
-    (setq extra (org-beamer-assoc-not-empty "BEAMER_extra" props))
-    (when extra
-      (setq extra (replace-regexp-in-string "\\\\n" "\n" extra)))
+    (setq org-beamer-environment (org-beamer-assoc-not-empty "BEAMER_env" props))
+    (setq org-beamer-extra (org-beamer-assoc-not-empty "BEAMER_extra" props))
+    (when org-beamer-extra
+      (setq org-beamer-extra (replace-regexp-in-string "\\\\n" "\n" org-beamer-extra)))
     (setq tmp (org-beamer-assoc-not-empty "BEAMER_envargs" props))
     (when tmp
       (setq tmp (copy-sequence tmp))
       (if (string-match "\\[<[^][<>]*>\\]" tmp)
-	  (setq defaction (match-string 0 tmp)
+	  (setq org-beamer-defaction (match-string 0 tmp)
 		tmp (replace-match "" t t tmp)))
       (if (string-match "\\[[^][]*\\]" tmp)
-	  (setq option (match-string 0 tmp)
+	  (setq org-beamer-option (match-string 0 tmp)
 		tmp (replace-match "" t t tmp)))
       (if (string-match "<[^<>]*>" tmp)
-	  (setq action (match-string 0 tmp)
+	  (setq org-beamer-action (match-string 0 tmp)
 		tmp (replace-match "" t t tmp))))))
 
 (defun org-beamer-assoc-not-empty (elt list)