Somehow the idea of starting "Windows: The Second European Community Film Festival" with several minutes of full frontal nudity didn't seem quite politic. Especially when a couple of dozen pin-striped executives from the festival's lone patron, R.J. Reynolds Industries Inc., were flying up from Winston-Salem, N.C., for the opening tonight.

According to some reports circulating last night at a reception Reynolds gave at the State Department, the Danes had been all for launching the festival with Esben Hoilund Carlsen's "Stepping Out," a comedy of manners and morals that's been called "a kind of sexual Nashville without the C&W country and western music." You'd expect the Danes to feel that way, somebody said, because the film is Denmark's contribution to the 26-film festival getting under way tonight at the American Film Institute Theater in the Kennedy Center.

Director Carlsen said he doubted being relegated to the number-two spot on the opening program had anything to do with the nude scenes in his film. "The nudity in it is very, very small . . . Not naughty, just fun," he said.

He suspected "Stepping Out" is second tonight because nobody had been certain whether Polish-born Jerzy Skolimowski, director of "Moonlighting," Great Britain's contribution and the first film to be shown tonight, was coming. "He's more famous than I am," said Carlsen.

Nudity, on the other hand, isn't a problem anymore, according to Carlsen.

"Nobody gets upset," he said. "A few years ago if you had a nude scene in a film it was something you discussed with the star for days. The whole set was emptied except for those people who had to take their clothes off. The first time I made a nude scene I took off my own clothes just to make the star feel she was not alone. I don't have to do that anymore."

Skolimowski's film about four Polish construction workers marooned in London's Kensington district during the Polish crisis took him only 11 days to write. Then it took him only 10 minutes to persuade actor Jeremy Irons to be in it. In May 1982 Skolimowski entered "Moonlighting" in the Cannes Film Festival--and won a prize.

"The Polish press said the film has definite high artistic qualities but disagrees with its political message. Obviously," said Skolimowski, once the enfant terrible of the Polish film industry and now the self-described "middle-age terrible." His film titled "Hands Up" was banned for 14 years, then was shown to the public for the first time at midnight on Dec. 12, 1981, at Warsaw's Palace of Culture.

"At dawn the next day, as people were leaving the cinema, tanks were there in the streets," he said.

AFI's festival represents 10 countries and runs through Feb. 21. Both Skolimowski and Carlsen will lead discussions following their films tonight.

"We have long had an interest in the arts, particularly the performing arts. We believe this is one of the ways we can contribute to the quality of life," said J. Paul Sticht, chief executive officer of R.J. Reynolds, which spent $53,000 to underwrite the festival and flooded the place with cigarettes and specially made ashtrays last night.