[priceless]

If you open up the "Canvases" bar, you'll see a little box to the right of the of the master or Canvas. Clicking that box allows you to pick the colour of the canvas.

That should do the trick. I find it helpful to do that when building images for powerpoint / keynote where I do often use a darker background.

Also, I sometimes simulate a gradient background by sticking in a box with a gradient into the master template.

HTH

Morgan