Just for the completeness of the reply in case someone wonders (like I used to):

• Walls have an Arc extent property that will curve a wall (+/- values).
• The easiest way to draw a room within a curved wall, is first to draw the walls, and then double-click with the Room-tool. Then the room will follow the wall.
• Rectangular windows and doors can be inserted in curved walls, but must be placed manually: adjusted depth so they penetrate the wall and exact angle to follow wall (use Alt to disable magnetism if you use mouse).

ok