Well I'm glad its not just me having these issues, thanks for the reply back dwin_ph, yet again Apple have released an OS without proper testing of the Accessibility features, the thing is these kinds of problems aren't hard to detect, anyone who uses the zoom feature in OSX for more than a few minutes will quickly hit these issues, so how on earth do they get through beta testing ????
The thing is I've been using OSX since the days of Tiger whereby there were issues on certain screens where zoom simply got locked and wouldn't work, this issue was still there in Leopard whereby you'd enter time machine (window flying througjh space screen) and yet again the zoom failed to work, that's quite an obvious flaw in the operating system and yet said flaw managed to carry through as far as Lion, whereby there were certain areas of the OS I simply couldn't zoom (Launch Pad, Time Machine, the login screen, Mission Control etc etc) the list goes on.
So imagine how thrilled I was when "finally" after sending dozens of bug reports to Apple's feedback section someone there actually listened and enabled zoon in Time Machine, Launch Pad, Mission Control etc and then for it all to fall flat on its face because now the mouse pointer disappears at will, especally when moving from screen to screen in Mission Control; again I cant help but feel ten minutes of someone who actually uses the zoom feature during beta testing would have picked this up in no time.
The thing is I love OSX, I was an instant convert, not least of which because the zoom feature was just so superior to that of Windows. I just wish that once and for all they'd fix it and get it right, as someone who's partially sighted there is nothing more frustrating than being denied access to a certain feature or part of the OS than finding out the zoom feature (the only thing that allows me to keep using a Mac) simply doesn't work.
Please Apple, sort this out and fix it once and for all. And if you need me to come work as a software tester to get all these issues ironed out then give me a call :-)