There is a new version of Docear available for download. It’s basically the (experimental) RC1 version done right. RC2 fixes a lot of bugs that were caused by the new workspace model with multiple projects, it features a refined and polished version of the Ribbon, fixes a lot of bugs in general and supports the standard PDF viewers of MacOSX (Preview and Skim) and probably a lot of other viewers as well!
If you are still using Beta9 of Docear, a lot of things will change and improve with this new version of Docear. However converting your old maps to this new format is a one-way process (you can’t use these files with Beta9 of Docear anymore) and the process itself might take some time, depending on the size of your mind maps. Please backup your files before upgrading to Docear RC2.