Speaking from the viewpoint of a new wine developer, the major hurdle, in my view, to contributing to wine is the lack of comments in the code, and the lack of whitespace. Wine is complicated enough, and the lack of comments in the code makes it more difficult. When trying to trace existing code to see how things work, there are very few comments to go off of. This hinders things, especially when trying to understand things that don't have any documentation written for them. Parts of wine might have one or two comments spread throughout the page, if you don't count the copywright info at the top of the page.