What's the Insider ring for the Windows client? Glad you asked. This will soon be documented but you get to test it out first. Essentially it gives you access to upcoming versions of the Windows client before they are available publicly so you can validate and raise the flag if needed. While we may update the public version on a monthly cadence, the Insider ring should get a new version about every 2 weeks. Versions that look good will get promoted to everyone. The recommendation will be to keep some admins/users on the Insider ring, similar to having some session hosts on Ring 0.
To get started, set the following registry entry and if successful the client's title will change to Remote Desktop (Insider). Key: HKLM\Software\Microsoft\MSRDC\Policies, Type: REG_SZ, Name: ReleaseRing, Data: insider.
Here's what's new in version 1.2.199:
The client is now available in 17 languages (Da-dk, De-de, En-gb, En-us, Es-es, Fi-fi, Fr-fr, It-it, Ja-jp, Nb-no, Nl-nl, Pl-pl, pt-BR, ru-RU, sv-SE, zh-CN, zh-TW)
The window title for desktop session now displays the desktop name
The client now uses .Net 4.6 so users on older Windows 10 won't need to install it