This was changed in Firefox 29. There is an add-on to give you back the Firefox 4 (or earlier) look. This article has the details: How to make the new Firefox look like the old Firefox.

Note that Firefox will only place the Tab Bar on the Windows title bar if the Firefox window is maximized. See also this pref on the about:config page.

• browser.tabs.drawInTitlebar

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

If you want to make the title bar visible then you can find that setting in the Customize palette window.

In current Firefox releases (29 and later) the orange Firefox menu button has been replaced by the three-bar Firefox Menu button at the far right end of the Navigation Toolbar and this button is always visible whether the Menu Bar is visible or hidden. A consequence of this position is that you no longer can hide the Navigation Toolbar.

• There is a star like button next to the search bar on the Navigation Toolbar to bookmark the current web page and a "Show your bookmarks" button next to it to open the Bookmarks in a drop down menu.
  You can find "Show All Bookmarks" to open the Bookmarks Manager (Library) at the bottom of this drop-down list
• If you bookmark a page then "Bookmark This Page" in the Bookmarks menu changes to "Edit This Bookmark"
• You can make the title bar visible via the "Title Bar" button at the bottom left in the Customize palette window

It is still possible to have the Menu Bar visible via the right-click context menu of a toolbar to have menus like the File menu with Print (Ctrl+P) and Print Preview and the Bookmarks menu available.

Changing the value of browser.tabs.drawInTitlebar put them back up top. Thank you.