Axel, I've resorted to running a cpu server inside parallels and connecting to it via the OSX-native drawterm. I need this in order to get full three-button support on my laptop.
I have not experience the effect that you're seeing under vnc, for me the graphics have always ran fine (including full screen up to 1920x1200 or somesuch), but I don't often have a 3-button mouse to plug in, so I stick with drawterm. I just verified that I also see no 32-bit modes in aux/vga -p's output.
