As you will be aware, the in-browser edition of BBCSDL uses the same 'simplified' interface as the mobile (Android and iOS) editions, because it shares some of their limitations - for example not being able to open multiple windows - and because it was expedient to do so. This interface is created by the touchide.bbc program in examples/tools/.
But the browser interface doesn't share all the limitations of the Mobile editions (for example there will commonly be a physical keyboard rather than a touch screen) and could be made significantly more functional. Some other BASICs that can run in a browser do indeed provide a much more sophisticated and convenient interface, and it makes BBC BASIC look bad in comparison.

One obvious capability that is not taken advantage of at all in the current in-browser edition is the possibility of opening another browser tab, something which has no direct analogy in mobile editions. For example one could, in principle, have a program's source code open for editing in one tab and the output from the program running in another tab, not dissimilar to the interface the desktop IDEs provide.
So it would be highly desirable to develop such an enhanced interface for the in-browser edition, and it could improve the way that BBC BASIC is perceived. But there is a major snag, my illness means that I am no longer capable of doing that on my own. I could hopefully contribute some aspects, but to take on the entire development, particularly the 'cosmetic' features (which I've never been good at), is beyond my abilities now.
So this is (I'm sorry to say) another plea for help. If somebody could collaborate with me, perhaps in designing the 'look and feel' of the interface and perhaps coding some aspects of it, it might be manageable. Unfortunately past experience suggests that nobody will volunteer, or probably even respond at all. But perhaps this time it will be different (one can only hope).

PLEASE HELP.