After several years on Megadrive side, I recently get hooked by the lil' Wonderswan.
I was looking for a way to homebrew develop on it and unfortunalty, no dedicated emulator include debug feature.
So I moved to MAME, since it include a full debugger and GFX Viewer.
Unfortunately, the GFX Viewer part isn't present, like most of the CONS system it seems.
And so began my journey on MAME driver update.
I must say, sorry, that it was VERY difficult to start and while I was about to stop, I finally was able to add GFX Viewer support.
and so I'm currently improve it step by step....

What is done
GFX Viewer for WS Classic
use of LOGMasked
(available on my MAME fork, wswan branch at https://github.com/KanedaFr/mame/tree/wswan)

What is in progress
Serial link support

My main reason to post of this forum is to be sure I do it the right way and, if interested, understand how to post my update to main branch, to allow any other people to use it.
I hope it's alright with the guidelines and that I will be able to at last give somethink back to MAME, after so many years using it for playing, hacking, etc....