What is Wine Staging?
Wine Staging is the testing area of winehq.org. It contains bug fixes and features, which have not been integrated into the development branch yet. The idea of Wine Staging is to provide experimental features faster to end users and to give developers the possibility to discuss and improve their patches before they are integrated into the main branch.
Wine Staging is maintained as a set of patches which has to be applied on top of the corresponding Wine development version. Package maintainers can decide if they want to include our full patchset, or only want to cherry-pick patches for specific bugs.
Pre-compiled Staging packages for most major distributions are available on the Download page. Instructions for downloading Staging are given under each distribution that provides it.
Building from source
Since Wine-Staging is maintained as a set of patches rather than a forked repository, the process of building is slightly different. You will first need a vanilla Wine source tree and the required dependencies; for instructions see Building Wine. Note that Staging adds some optional dependencies which are necessary for certain additional features. You will also need the Staging "source"; this can be cloned or downloaded from the GitHub page.
Once you have obtained the sources, you will need to apply the Staging patches of your choice (or all of them) on top of the Wine source tree. You can do this using the provided patches/patchinstall.sh script; see its options with --help for detailed instructions. If you apply patches manually, take note that you will also need to run autoreconf -f and tools/make_requests, as such generated changes are not included in Staging patches. Be warned that an individual version of the Staging repository will only successfully apply against the upstream Wine commit it was last rebased against.
After you have applied patches, compilation proceeds as usual for upstream Wine; refer to Building Wine for detailed instructions.
Here are some links to the most important topics.