Well you helped us find an obscure bug. I’m guessing not many people use the rounded corner menus. It is a bit of an old-fashioned look.
But I appreciate your patience, and the fact you reported your issue(s). You’ve managed to find two problems, one which has been there a long time (the bg color on the editor).
But it will be fixed in 3.0.5.
And Merry Christmas to you, too.