Everything seems to work without `overflow: hidden` here, including the arrow. Terry has an outstanding PR #735 that re-aligns the arrow with the button, as well as eliminates some other visual artifacts and moves the button and the menu slightly to the left, so they look better (the menu doesn't create an appearance of spilling over the right edge of the window). It also makes the arrow clickable, so the whole menu button works as expected. I suggest we combine Terry's PR and a subset of yours as discussed elsewhere.