instance property Component#opacity
Component#opacity → Number
A percentage value (between 0.0 and 1.0, inclusive) that describes the
Component
's opacity. Setting this value to 1.0 (default) will
make the Component
fully opaque. Setting to 0.0 will make it
fully transparent, or invisible. Setting to 0.5 will make it 50%
transparent. You get the idea...