B4A's visual form design function is indeed from 2015 to nearly 10 years has not made much progress, if you can do most of the function can preview, add pictures in the interface designer, modify the button title can immediately see good results.
Perhaps the most powerful UI designer is the Web version, which can be designed to open a web page and finally convert it to JSON format and regenerate it into a Bal format interface document.
The other is like the mobile version of PS, which directly designs and adds various buttons, pictures and other controls on the phone, and really sees the effects, animations, playback sounds and so on.