Hi Rastin, I have just tested the 4.0 Embryo release.The installation was straightforward and until now I have found no issues at all.The new menu works fine, but it would be nice to have a few sample links in templates/shiraz/html/menus/main.php by default to show how the menu renders. I just copied the previous <ul class="nav " data-behavior="BS.Dropdown">...</ul> from my existing installation.
Thank you Sina, yes a commented out code example would be a good idea. I'm glad that you found the solution. What is the url to your project if you don't mind me asking? If you don't want to share it publicly, pelase feel free to PM me.