If you find an issue, a pull request is always better than a bug report. Please fork and submit your code fixes.
If you want to build some new features, we have a roadmap.md of features we want. You can add features you want there, or just code the feature and send a pull request.
$ git clone https://github.com/jonrohan/ZeroClipboard.git
$ cd ZeroClipboard/
$ make
$ make test