Rob,
Anyway this was a temporary workaround with those PD9 builds at that time.
Since then, this is fixed and supported by a GUI switch in the VM configuration and you should not attempt to change anything in the registry anymore.
See VM Configuration, Hardware, Keyboard&Mouse section, you'll find it easily. I had to UNCHECK that new setting (about smooth scrolling) to get things working like in previous versions (with Visual Studio 2012 & 2013 which doesn't itself support support smooth scrolling correctly - a pity).
Last edited: Nov 21, 2013