Questions about ExtendedTabbedPage in Xamarin Forms XLab project

Hi guys,

I'd like to show a badge on the Tab Bar of Tabbed Page. I noticed that ExtendedTabbed Page supports in XLab project supports this. However, the badge can be only loaded in the contructor, but not set any value in the method or function. Do you have any idea about this issue?

ExtendedTabbed Page wiki:
https://github.com/XLabs/Xamarin-Forms-Labs/wiki/ExtendedTabbedPage

Thanks.