Cause of http://crbug.com/428610

Adwaita-gtk-2.0-gtkrc

style "menu_item"
{
	xthickness	= 2
	ythickness	= 4

        # HACK: Gtk doesn't actually read this value
        # while rendering the menu items, but Libreoffice
        # does; setting this value equal to the one in
        # fg[PRELIGHT] ensures a code path in the LO theming code
        # that falls back to a dark text color for menu item text
        # highlight. The price to pay is black text on menus as well,
        # but at least it's readable.
        # See https://bugs.freedesktop.org/show_bug.cgi?id=38038
        bg[SELECTED]    = @selected_fg_color