Colours

The rgb object:

An rgb is just a 32-bit unsigned long integer.
The format of the 4 bytes is ARGB (Alpha/Red/Green/Blue).
The maximum value of any byte is FF (decimal 255) and minimum value is 00.
The top-most byte stores the alpha channel transparency information. 00 means opaque, FF means fully transparent.
The next three bytes give the intensity of red, green and blue light.
So 0x00FF0000 is bright red, and 0x007F007F is dark purple.

Predefined colours:

#define Black         0x00000000
#define White         0x00FFFFFF
#define Grey          0x007F7F7F
#define LightGrey     0x00BFBFBF
#define Transparent   0xFFFFFFFF
#define Red           0x00FF0000
#define Green         0x0000FF00
#define Blue          0x000000FF
#define Cyan          0x0000FFFF
#define Magenta       0x00FF00FF
#define Yellow        0x00FFFF00