Be advised. Today I have used B4A Bridge to debug a little app of mine. After running the app the launcher crashed and the error: "System.ui has stopped" pops up continuously. Even after reboot .
I am using a Samsung Galaxy S6 with Android 5.1.1.
So I did a hard reset and after reinstalling all my apps and data I tried again with the same results. I had to do the hard reset again because the phone becomes unusuable.
I don't know if this is an Android bug or a B4A's. In the meantime be careful.