[bug] beamer export envargs for column not working properly

[Eric S Fraga <ucecesf@ucl.ac.uk>]

Hi,

I am trying to create a beamer slide which has two columns.  The second
column should only appear after a while (the 6th uncovering operation).
In latex, I would do:

: \begin{column}<6->{0.4\textwidth}

say.  In org, I would expect to be able to get this latex code generated
by the following:

--8<---------------cut here---------------start------------->8---
***** column heading			      :BMCOL:B_block:
      :PROPERTIES:
      :BEAMER_col: 0.4
      :BEAMER_envargs: c<6->
      :BEAMER_extra: 
      :BEAMER_env: block
      :END:
--8<---------------cut here---------------end--------------->8---

according to the info documentation (Beamer class export).

However, this does not work: the "c<6->" is placed verbatim in
the \begin{block} that comes after the \begin{column}.  Furthermore, if
I ask for the heading to be ignored (instead of defining a block), the
envargs are lost completely!

Thanks,
eric

-- 
: Eric S Fraga (GnuPG: 0xC89193D8FFFCF67D) in Emacs 23.2.1
: using Org-mode version 7.3 (release_7.3.104.gf692)