By the way, the Z-adress (screen shifting) and contrast change glitches are still present in the newest versions of Wabbitemu.
Look at what I mean in the screenshot below. Only the run indicator Y position changes. In some occasions, like when the final boss dies, during the earthquake effect there, stuff displayed with Output gets displayed at the right position, which implies that WabbitEmu's Z-adress emulation doesn't refresh the screen content, but displays new stuff at the right locations.
Another example of the z-adress bug is at http://www.youtube.com/watch?v=96XuVDkZbUs
(when the power flickers constantly in the underground shelter, the screen is supposed to shake).
Also I made a screenshot of the contrast glitch in Camstudio then converted it to GIF. Past 7 it gets lighter.