JDK 7: Shaped and translucent windows
Just as life doesn't always fit
neatly into a box, neither does everything you want to show on
screen. Wanting to see behind what you're looking at is really
just part of the human condition, and perhaps why the use of translucency
in GUIs has become so popular.
The ability to create shaped and translucent windows was first released
in Java SE 6u10, but you had to use a private API to do so. With
port of all the Java SE 6u10 features into the JDK 7 codebase,
now you have a public API to do this.
new article gives a 100% translucent picture of the capbilities,
and is a good companion to this
older, but recently updated technical article.