Sticky Header by ThematoSoup allows you to add sticky header to any WordPress theme.
it would be great if it shows sub-menus!
This could be a very nice and useful plugin because it makes WordPress much more usable as a general website CMS. If... it worked in Internet Explorer 11. Still about 40% of my audience. I could tell Microsoft that something is wrong with their browser but they won't listen ;)
The theme Superhero includes a fixed header and that one works with IE11.
I am unable to align the menu to right or left or center, besides that the menu is unable to give me a drop down even...things can be done with css but its time consuming....otherwise a good plugin.