It is a supreme shame what you have done to multi monitor support, and color calibration.... There is such an enormous population of Mac Users that are using for Graphics and other visual purposes.. Photographers, Graphic artists, Film producers, and the list goes on.. Many, if not all of use use our programs spanning across multiple monitors to maximize productivity, our workflow depends on it.. We also rely heavily on correctly calibrated, and professionally calibrated monitors.. With your recent, seemingly unnecessary changes to this with Mavericks, you have disrupted and hopefully not permanently changed and hampered all of our workflows. This is extremely troubling.. To go many years back in time, to not allow programs to span across multiple monitors, is a step that seems to defy reason and logic... Please return what should be a standard function for our productivity... and fix the Color calibration as well.. Sacrificing the ability to correctly calibrate secondary monitors by adding a Windows 95-esk user level color calibration to satisfy some unseen need or polling, is again, beyond comprehension and logic..