Thank you for telling this 
It’s really unlikely that these will change in (ST)emWin.
I know about GUIX but haven’t tried it yet. To be honest it looks good, but I wonder why it didn’t get any traction once it’s developed by Microsoft. Anyway, I saw that Renesas is using it.
It has a UI editor, but finally LVGL also will have one end of this year. You can try the beta version until that if you are interested.