In most islamic societies there is the "official" and "unofficial" and they sometimes differ widely. jno is correct that Saudi Arabia and Iran are two of the countries where wearing this clothing in public (i.e. not covered) is an offence or at least seen as offensive, unlikely to go unpunished. However, in private situations in these same countries, such as within a walled garden or in a house, you should not be surprised to see lots of local women wearing T-shirts and other things forbidden on the street or in shops - and in mixed company too. The time has not yet arrived where the unofficial is officially accepted, but I have no doubt it will eventually. Even religious masters die, just like the rest of us, and are replaced by new ones who have a different outlook.