I am not able to find the below icon in ImageMSO. I noticed that Microsoft have used the same icon in their Office applications. So I want to know whether it's part of ImageMSO.
Thanks!
Yes, it is part of the Office Fluent UI Command Identifiers. The imageMso
name you are looking for is "WhatsNewRecentUpdates" as in:
<button id="rxbtnMyButton" label="Super Megaphone" imageMso="WhatsNewRecentUpdates"
onAction="rxbtnMyButton_click" supertip="Generate a deafening sound." tag="boom" />
You can find all of Microsoft's Office 2016 and Office 365 Fluent UI Command Identifiers in this GitHub repository:
Office 365 Current Channel Fluent UI Command Identifiers
Edit 1/11/2019
Updated the above link per Ben's comment.