Multi monitor support with Ogre 1.8 seemed to be sketchy at best. It improved with Ogre 1.9 and up, but I believe Purebasic is still using Ogre 1.8.
Last I heard even with the newer versions of Ogre they still had issues with mac and linux because of some monitor problems or something similar. So, it was windows only which the PB community might not be thrilled about.
I haven't been following Ogre much these last two years so they may have fixed these problems.