[wix-users] Preserve registry values on Major Upgrade

[Luca Bacci]

Hello, I have many registry values that I create on install and are values
for user preferences / customization. In my wix project I have a component
with many registryvalue elements

<Component Id="cmpRegSettings" Directory="TARGETDIR" Guid="*">
  <RegistryKey Key="Software\My\App\Settings" Root="HKCU">
    <RegistryValue Name="A" Value="120" Type="integer" />
    <RegistryValue Name="B" Value="80" Type="integer" />
    ...
  </RegistryKey>
</Component>

Their value are set to the default when installing for the first time. I'm
now implementing major upgrade and I need to leave existing preferences as
set by the user. What's the best way to do it?