Yes, that is the intended functionality. If you mouse-wheel to set the percentage to it's LOWEST value, the entire render bitmap should be shown. Then when you mousewheel scroll to zoom - it should zoom in on your mouse position.The mouse wheel changes only the percent of view (Size, see screenshot), nothing else. I have tried the wheel, the pressed wheel while rolling, right mouse button + wheel, left mouse button + wheel, middle mouse button + wheel, shift + wheel, control + wheel, cmd + wheel and so on. But always the percentage is changing.
I wonder if maybe you have your OSX mouse controls setup differently to mine, which is causing the issue?
Paul