I am having this weird issue with Mail in Mavericks. Running a 15" 2012 Macbook Pro with an external monitor connected. Have chrome on full screen on my Macbook Monitor and Mail, Reminders and Calendar up on the external display. When I click to compose a message (or reply) in Mail, it opens up the new message window on the external display, but for some reason it moves my main macbook display over to a blank desktop (i.e. slides over one space) and doesn't stay on Chrome. Anyone else having this issue or know how to fix it?