I have screen sharing enabled between my home mac mini and my work iMac. I am able to log in from home to work and perform actions, but the mouse pointer on the remote screen is off by an inch or so. keyboard functions work fine, but where it looks like my mouse is hovering and where the imac thinks it is is off by about an inch. is there a tool or a way to calibrate it? also, is this black space supposed to be at the top? it is about the same amount that the cursor is off... is this a problem, with the screens?