On the close buttons:

That bit of the program was removed, so the preference no longer has any effect and there is no other built-in preference for it.

You can use an extension to change the close button style, see How do I restore the "close tab" button to the END of the tab bar?

Or it's possible that Tab Control will be updated; I'm not familiar with that extension.

(It's also possible to suppress elements by applying custom style rules to Firefox's UI. However, I'll spare you the details since I haven't worked out what the rule would be.)

On the close button overlapping another tab:

I'm not sure why this is happening. If you have the patience to experiment with it, can you isolate the zone where it looks like a click should switch tabs but instead it is hitting the close button?

Actually the style rule to suppress the tab close buttons is simple:

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
.tab-close-button{
  display:none !important;
}

Custom style rules can be applied to the user interface using either of two methods:

(1) Create or edit a userChrome.css file. For more information, see: http://kb.mozillazine.org/UserChrome.css

(2) Install the Stylish extension, create a new blank style rule, and then paste the above code.

I generally use Stylish because it has a handy Preview feature that makes it easy to tweak rules when you're making complicated changes or exploring.

Only the value of 3 for this pref is problematic as this would require JavaScript code to create a toolbar button. The value of 0 (actual) and 2 (no close buttons) can easily be achieved with code in the userChrome.css file.

Note that the current version of the Classic Theme Restorer extension has a setting for the tab close buttons in the Tab pane.

• tabs closebutton restored: https://addons.mozilla.org/firefox/addon/tabs-closebutton-restored/

There are also several add-ons that can do this for you.

Among them;

Rights To Close {web link} Right double-click anywhere on web page to close current tab.

Close Tab by Double Click {web link} Allows you to close tabs by double-clicking using the right mouse button.

jscher2000,

Thank you for your fix, worked just fine.

I don't know why Firefox removes features like that, but doesn't add other similar simple features (ex. open tabs on right, close tab selects left).

It seems now even the simple features they had are now going to extensions and user css files. I wonder if they even made a note of this in their change logs.

When you look at the release notes page (https://www.mozilla.org/firefox/31.0/releasenotes/), you see some highlights, but there is a link to view "all" changes which leads to a listing of hundreds of items in the bug tracking system. I think this is as close as you can get to a change log.

I'm still trying to figure out why the add-ons bar was removed. As are many hundreds of other users.