A playwright by trade, Václav Havel is better known over here as Czechoslovakia's leading dissident. After 1968, under the Soviet-imposed "normalization", he was charged with subversion and his works were banned. He was finally imprisoned in 1979 for his activities in connection with Charter "77 (founded to monitor the Government's observance of its own laws) and VONS, the Committee for the Defence of the Unjustly Prosecuted. He was released, seriously ill, in 1983. Now fifty years old, he still lives under constant surveillance. What that means may be gathered from Tom Stoppard's play Professional Foul.