The Windows Insider app for phones has received another update, just a few days after the last one, and again there is no change log in sight. This update appears to be showing for those already on a Windows 10 mobile preview, but not for users still on Windows 8.1. Several users are reporting improved local language support within the app, though there is nothing official from Microsoft about how far that expanded.
Full story from the WindowsCentral blog...
of windows 10 mobile- Notification and Action centre of current build (i.e_ build 10166) in which every thing could be easily seen i.e_ Notification of messaging and facebook and WhatsApp. I even wanna know that can we directly reply to a message received by messaging or by even WhatsApp, through action centre? If possible kindly upload a screenshot of action centre. I would be highly obliged and thankful. Thank you 
Facebook
Twitter
Instagram