## Link to GitHub Issue or related Pull Request, if one exists
#676#452
## Description of change
When spice SDK or API sets or clears button and analog override, we
don't tell MDXF about it, so it may fall behind. This is a special case
for DDR MDXF I/O emulation. For Naive/Xinput I think we are getting
lucky because they usually also generate WM_INPUT events.
Update the C++ SDK sample to provide more interesting example of
emulating DDR arrows with the keyboard.
## Testing
bicarus
1957917270