If you have seen the DV window opened in flight on either a 777 or an A320 in hot climates,you were dreaming. These aircraft have extremely efficient pressurisation and air conditioning systems, capable of coping with extremes of temperature. The DV window would only be opened in an extreme emergency involving smoke in the cockpit. I am not aware of a single incidence of this situation, on either aircraft. In fact, I am not even sure that the A320 windows can be opened in flight, I do not fly it......