Text scaling to page width
This script will make the text as big as possible, in relation to the canvas width:
grid = ximport("grid")
size(470, 430)
fill(0)
txt = "hello"
x = 20 # text position from the left edge
y = 45 # text position from the top
# Draws the text as wide as possible:
p = textpath(txt, 0, y)
p.fit(x, y, WIDTH-x*2, 1000)
drawpath(p)