_NET_ACTIVE_WINDOW buggy timestamp

[Lanoxx <lanoxx gmx net>]

Hi,

when I manually start mutter or metacity in the terminal with the 
--replace option, then I always see errors like this:

last_user_time (39093728) is greater than comparison timestamp 
(16350305).  This most likely represents a buggy client sending 
inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to 
work around...

Is there any way to find out which application is causing this problem? 
Or is it somehow possible to let mutter, metacity print the name of the 
program that is responsible for this?

Otherwise, how can we fix this?

Cheers
Lanoxx