That lead me to come up with a prototype of a drag and drop application that provides you with feedback about where you can drop your items as soon as you start dragging them. This way, you don’t need to hover your mouse over all elements to see if the mouse shape changes. Instead, using the timing framework, drop zones are animated onto the glass pane to indicate where you can drop the object.

Technically, this is done by iterating over the content of a window hierarchically. As soon as a zone is identified that is a drop zone, it is marked as such. When all zones have been discovered, they are all highlighted, in this example with a simple rectangle, but you could enhance the example to create effects similar to Apple’s Exposé.

The application was developed for Java 6 and includes source code, build files and the necessary library.

Download: swing-dropzones.jar