Prelim to defining a fancy background

I want to add some subtle affects to the background. For that, I will use
MetaPost. As a first step, I redraw the colored background using MetaPost. See
the MetaFun manual for details.
Create a subtle red border around each slide

I like this subtle background, but this example shows that you are free to pick
any MetaPost graphic that you like as a background.
Add a visual counter for page numbers

See the documentation of t-visualcounter for details.

- http://modules.contextgarden.net/dl/t-visualcounter/doc/context/third/visualcounter/visualcounter.pdf