Hi Ron,
Menu widget does not have the "Text" property to change the font's size. I'll consider adding it. What you can use as a workaround is the font wiki syntax which looks like this:
%(font:14)&File%,%(font:14)&Edit%,%(font:14)&View%,%(font:14)~&Window~%,%(font:14)&Help%
Let me know if this works for you.