Flash Player 9 and later, Adobe AIR 1.0 and
You can control the transparency
of a display object to make it partially (or completely transparent),
or change the transparency to make the object appear to fade in
or out. The DisplayObject class’s alpha property
defines the transparency (or more accurately, the opacity) of a
display object. The alpha property can be set to
any value between 0 and 1, where 0 is completely transparent, and
1 is completely opaque. For example, these lines of code make the object
named myBall partially (50 percent) transparent
when it is clicked with the mouse:
myBall.alpha = .5;
You can also alter the transparency of a display object using
the color adjustments available through the ColorTransform class.
For more information, see Adjusting DisplayObject colors.