Hi,
I am currently using the B4A Designer to design my UI.
If I am connected to my device by WiFi, I can then press F2 which will open the designer app on my Android device and I can see the UI on my phone as I design the UI in the designer on the computer.
Currently if you close the designer on the computer (or disconnected from the device in the designer on the computer) the UI is still showing on the phone.
A good feature would be if you close the designer on the computer, to then close the designer app on the phone since we are no longer editing the UI since the designer on the computer is now closed or disconnected.