Samsung updated to Pie, now showing a chat head pop-up (disable it / make it work)

This is a Samsung specific feature, it is not related to Textra. 

This Samsung feature is only intended for apps that support Samsung multi-window, which Textra doesn't.

Either disable this feature, see Android Settings > Advanced features > Smart pop-up view > Textra = OFF

Or configure it to mostly work (it's flaky at best), see Textra Settings > Customize Notifications > Define Notification Actions > Tapping Opens = Quick Reply no Keyboard.

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