Color - alpha and RGB

[Maciej_Augustyniak]

Hi,
In helpdesk "Drawing and Animation" is:

so alpha has 00 - FF, so 256 values. And there is "alpha-red-green-blue". But alpha is the fourth value on the list of RGB code.
In "MIT App Inventor Color Blocks" is:

But probably default alpha is 256? It is a bug or my thinking is wrong?

[TIMAI2]

0 - 255