Creating figure with negative position for secondary monitor (on mac)?

i see some questions for this exact issue, but resolved for windows - i'm on a mac and can't translate the answers across.

i want to have figures come up on my secondary monitor, on the left of my main screen. the relative positions of my monitors are:

[-1439 1 1440 900; 1 1 1680 1050]

if i ask for: figure('position', [-1000 x y z])

i get the corresponding figure from: figure('position', [1 x y z])

ie the negative value is ignored. before i updated my matlab version, this worked just fine. any clues?