On Wednesday, 31 May 2017 at 10:04, Jean-Christophe Helary wrote:

[...]

> And I get the expected behavior in GUI emacs. So it's really an issue
> about ESC that is not recognized in GUI mode for *some* bindings in
> org-mode.

I can actually confirm this on quite recent org (as well as 8.2.10 as
bundled with emacs 26.x) on Linux as well.

Comparing Alt-left with the ESC key followed by left arrow gives this
using C-h c:

: <M-left> runs the command org-metaleft
: ESC <left> (translated from <escape> <left>) runs the command backward-word

with emacs -Q in GUI mode.  Have not tried terminal mode.

As Jean-Christophe has said, this seems to be independent of the window
manager.  For completeness, I am using ratpoison.

-- 
: Eric S Fraga (0xFFFCF67D), Emacs 26.0.50, Org release_9.0.6-425-gf4fca1