The Stickies source code is available under the Apache 2.0 open source license. You should read and agree to the complete license before downloading or modifying the source code.
The source code is hosted on Google Code, and it was developed with Microsoft Visual Studio .NET 2005 in C#. To contribute a patch to Stickies, check out the source code from the Google Code Subversion repository, and send the patch to Bret Taylor at btaylor@gmail.com.
If you have any questions about the structure of the source code, don't hestitate to email me.