[matplotlib-devel] contour_demo problem

John,
When running coutour_demo.py with the Cairo backend I get:
 File "matplotlib/figure.py", line 338, in draw
 for a in self.axes: a.draw(renderer)
 File "matplotlib/axes.py", line 1307, in draw
 self.legend_.draw(renderer)
 File "matplotlib/legend.py", line 181, in draw
 h.draw(renderer)
 File "matplotlib/lines.py", line 266, in draw
 gc.set_foreground(self._color) # problem
 File "/matplotlib/backends/backend_cairo.py", line 421, in set_foreground
 self.ctx.set_rgb_color(*self._rgb)
TypeError: Context.set_rgb_color() takes exactly 3 arguments (4 given)
It looks to like the frontend (lines.py) is working with rgba colors
and passing the rgba color to the backend which is expecting rgb color.
colors.colorConverter.to_rgb(fg) is also a problem because for rgba input
it returns rgba not rgb.
One solution would be to change the last lines of colorConverter.to_rgb(fg)
from
 self.cache[arg] = color
 return color
to
	color = color[0:3]
 self.cache[arg] = color
 return color
To ensure that to_rgb() actually gives rgb and not rgba.
What do you think?
Steve