Last Friday, Microsoft released another "Redstone 4" Insider Preview for Windows 10. This is the secondrelease since the Fall Creators Update was pushed out to the public, and looks like being the release that re-starts the MS weekly release schedule.
There's not so much that's new in this release, but there are a *hell* of a lot of fixes for stuff that broke in the previous, 17035 release. One new feature of note though is the SDR brightness on HDR hardware control. As Microsoft put it:
Adjust the brightness of SDR content on your HDR display: Starting with Build 17040, Windows now lets you adjust how bright SDR content appears when running in HDR mode on the desktop. On an HDR capable system, you will see a slider in the “HDR and advanced color settings” page under Settings > System > Display. This is one of the improvements to HDR image quality that we have planned based on feedback from Insiders.
In addition to this, there's a few more input and handwriting tweaks, plus those aforementioned bug fixes. Here's the complete listing: Windows 10 17040 release notes