As the title said, is there a way to tweak this feature in elementary OS? Menu bar of every application should show on the top bar like OS X.
2 Answers
elementary OS does not support a global menu bar like Ubuntu or OS X. elementary apps do not use a menu bar, and apps that do use a menu bar display the bar in the window where the developers of the app intended it to display.
Any hacks or workarounds to extract menu bars from applications and display them in a panel are not supported and very likely will break your install (as has been seen several times on this Stack Exchange and Launchpad).
This is not supported now, but it could be a goal that a lot of people would appreciate. I personally would contribute towards a bounty for this. (I'm already an elementary os supporter)