Draws a rectangle with rounded corners. The current pen is used for the outline and the current brush for filling the shape.
Draws a rectangle with the given top left corner, and with the given size. The corners are quarter-circles using the given radius.
If radius is positive, the value is used as the radius of the rounded corner. If radius is negative, the absolute value is used as the the proportion of the smallest dimension of the rectangle (so the corner can be a sensible size relative to the size of the rectangle, and avoids the strange effects X produces when the corners are too big for the rectangle).
Restrictions on the magnitude of drawing coordinates are described with wx:dc%.