dbl-click on desktop doesn't work anymore with Windows+10 latest preview 10.0.16299.15
If you're beta-testing Windows and something which used to work no longer does, you're meant to tell Microsoft so they can fix it and avoid breaking compatibility in the final release.
This is why they let people beta test Windows.
On our side, beta versions of Windows change too much for us to spend time fixing issues related to them, which Microsoft may (and generally should) fix in a later beta. Our time is better spent in other work, from experience.
We ask that people only report issues that occur with released versions of Windows, and report issues caused by pre-release versions to Microsoft.