1. Press Alt+V
2. Select Toolbars
3. Click on Customize
4. You will see a New Tab icon in the dialog box
5. Just drag it next to your tab.

Well, i already knew about the Tab icon in the dialog box before. But i didn't know (and even hadn't expected) that i can drag an icon from the dialog box to the tab area (like described in step 5 of the above solution). Amazing.

@sunveer: Thank you

I want the new tab icon to appear on the tabs bar, just to the right of the last tab, as it always used to. I've installed 4.0 on three machines: an XP netbook, a Vista notebook, and a Win 7 desktop. On two of them the + appears on the tab bar as always, but on the Win 7 desktop it does not. I've used the customize toolbars function as described above. I can put a new tab icon nearly anywhere else, but I can't make it appear to the right of the last tab where I always look for it. What's up with that?

Sorry people...

Firefox 4 Windows shipped with a "display bug" in it.

There is NO New Tab / Open New Tab or etc. icon IN the Firefox 4.0 "Customize Toolbar dialog", at least in the Windows shipping code.

The New Window icon is there in the dialog, but NOT New Tab. In fact, there seems to be everything BUT the missing New Tab Icon in the Dialog.

The programmers left it out by error, thus there's nothing there to drag onto the toolbar.

If your copy of Firefox 4.0 DOES have the New Tab / Open New Tab icon in the Firefox 4.0 Customize Toolbar dialog, then you are using a version of Firefox 4.0 shipping that no one else has.

PLEASE for the Mozilla programmers to rectify the mistake of the missing New Tab icon at their earliest convenience.

Joe Knoxville, TN Skype: joerotello

Regarding this matter, FF 4 user cor-el posted elsewhere:

You can drag the New Tab (+) button from the Tab bar on another toolbar to make it appear there.

If you do not see the New Tab button on the tab bar then click the Restore Default Set button.

See also:

   http://kb.mozillazine.org/Corrupt_localstore.rdf  >>

Thanking cor-el for the post, HOWEVER:

On most all Firefox 4.0 installs, the + Open in a New Tab icon is NOT movable at all.

It can NOT be dragged anywhere, no matter what one does, which means it can not be placed in any active Toolbar..

The + being discussed here is the one that normally appears in-line with the Tab bar of open webpages just to the right of these tabs, in the upper right screen section, just to the right of the > symbol.

This is the problem expressed mainly in the FF4 Windows OS version.

Joe