Here's an easy one: Loop to change bkgcolor

[Peter Lundh]

Hi, all. After a longish time away from Revolution I know have to make a
very simple utility to help me characterize and calibrate a LCD display.

I have to measure the light emitted by the display with a spectrophotometer.
Against a grey background (128,128,128) I have to measure the light from a
300x300 px rectangle. I want to make several measurements at increments of
15 (0,0,0  15,0,0  30,0,0 etc) of each colour. Since the spectrophotometer
is at some distance away from the from the display I want to make the
process of changing the colour as automatic as possible. That is, each time
I hit the return key, or pageDown key the value 15 is added to the
backgroundColor until it's value reaches 255, after which it starts adding
15 to the second (green) value - 0,15,0  0,30,0  0,45,0 etc. I would like it
to loop through the R, G and B channels after which it does the grey levels
(15,15,15  30,30,30  45,45,45 etc).

Could anyone please show me how to increase the R, G and B values each time
I hit the returnkey.

Many thank in advance.

-Peter
-- 
Peter Lundh
E: simran at teleline.es
UK