How do I set the tab bar to be besides the Fx menu button when Fx' window is maximized? (v12 installer changed my UI layout)

The best way that I found several versions back was to modify the userChrome.css. You may have to snag the userChrome-example.css and rename it userChrome.css to actually activate it. Here's my modified userChrome.css. Sorry for the long post...

/*
 * Do not remove the @namespace line -- it's required for correct functioning
 */

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to XUL */


/* ----------------------------------------------------------------------- */
/* ----------------------  URL Bar & Status Panel  ----------------------- */
/* ----------------------------------------------------------------------- */

/*Remove magnifying glass button from search box */
.search-go-button { display: none !important; }

#urlbar,
#search-container .searchbar-textbox,
.tabs-newtab-button {
opacity: .25 !important;
}

#navigator-toolbox > #PersonalToolbar {
background-color:#dae0ee !important;
color: light-grey !important;
opacity: .65 !important;
}

#urlbar:hover,
#search-container .searchbar-textbox:hover,
.tabs-newtab-button:hover {
opacity: .8 !important;
}

#urlbar[focused],
#search-container .searchbar-textbox[focused],
#navigator-toolbox:hover > #PersonalToolbar {
color: black !important;
opacity: 1 !important;
}

/* highlight private mode and HTTPS URLs */
#main-window[privatebrowsingmode=temporary] #urlbar {
    background-image: -moz-linear-gradient(rgba(153,38,211,.5), rgba(105,19,163,.2)) !important; 
}

#urlbar[level="high"] {
    background-color: #D0F2C4 !important; 
}

/* Keep the status bar from truncating URLs */
statuspanel {
    max-width: 100% !important;
    opacity: .6 !important;
}

/* ----------------------------------------------------------------------- */
/* ----------------------  Main Menu Appearance  ------------------------- */
/* ----------------------------------------------------------------------- */


#toolbar-menubar {
    padding-left: 110px !important;
    margin-right: 110px !important;
    padding-top: 8px !important;
    margin-top: -30px !important;
}

#navigator-toolbox #TabsToolbar {
    margin-left: 88px !important;
    margin-right: 110px !important;
    padding-top: 8px !important;
}


/* ----------------------------------------------------------------------- */
/* ----------------------  Firefox Button  ------------------------------- */
/* ----------------------------------------------------------------------- */


#appmenu-button-container {
    position: fixed !important;
}

#appmenu-button dropmarker {
    display: none !important;
}

#appmenu-button {
    background: none !important;
    color: orange !important;
}

#appmenu-button:hover,
#appmenu-button[open] {
  background-image: -moz-linear-gradient(rgba(255,255,255,.8), rgba(215,215,215,.2)) !important ; */
    color: orange !important;
}

/*  background: rgba(255,255,255,.8) !important;
    color: black !important;
    font-weight: bold !important; 
}       
*/

/* orange button 
#appmenu-button {
    background-image: -moz-linear-gradient(rgba(247,182,82,.5), rgba(215,98,10,.2))  !important;
}

#appmenu-button:hover,
#appmenu-button[open] {
    background-image: -moz-linear-gradient(rgba(247,182,82,1), rgba(215,98,10,.7))  !important;
} 

*/

/* ----------------------------------------------------------------------- */
/* ----------------------  Tab Bar Appearance  --------------------------- */
/* ----------------------------------------------------------------------- */

/* Hide pulldown on end of tab bar
.tabs-alltabs-box,
.tabs-alltabs-button { 
    display: none !important; 
}
*/
/*
.tabbrowser-tab[selected] {
    background-image: -moz-linear-gradient(rgba(255,198,150,.4), rgba(247,182,82,.9))  !important; 
} 

.tabbrowser-tab:hover[selected] {
    background-image: -moz-linear-gradient(rgba(247,182,82,1), rgba(215,98,10,.7))  !important; 
    font-weight: bold !important; 
}
*/


tab {   
opacity: 0.25 !important;
}

tab[selected="true"] {     
opacity: .90 !important;
color: black !important;
font-weight: bold !important; 
}

tab:hover {
opacity: 1 !important;
font-weight: bold !important;
color: orange !important;
}


/* ----------------------------------------------------------------------- */
/* ----------------------  Private Browsing Mode ------------------------- */
/* ----------------------------------------------------------------------- */


#main-window[privatebrowsingmode=temporary] #appmenu-button  {
    background-image: -moz-linear-gradient(rgba(153,38,211,.5), rgba(105,19,163,.2)) !important; 
} 

#main-window[privatebrowsingmode=temporary] #appmenu-button:hover,
#main-window[privatebrowsingmode=temporary] #appmenu-button[open] {
    background-image: -moz-linear-gradient(rgba(153,38,211,1), rgba(105,19,163,1)) !important;
}

#main-window[privatebrowsingmode=temporary] .tabbrowser-tab {
    background-image: -moz-linear-gradient(rgba(205,100,225,.5), rgba(255,200,255,.8)) !important; 
}

#main-window[privatebrowsingmode=temporary] #PersonalToolbar {
    display: none !important; 
}

/*
#PersonalToolbar {
    visibility: collapse !important;
    opacity: 0.2;
   -moz-transition: visibility 4s, opacity 4s ease !important;
   }

#navigator-toolbox:hover > #PersonalToolbar {
    visibility: visible !important;
    opacity: 1;
    -moz-transition: visibility !important;
   }
*/

Oh... you'll have to un-do the transparencies and changed Firefox button appearance if you don't like them this way. Also, I never maximize the window, so this doesn't work perfectly under those circumstances. There's a way to fix that, but I never worried about it.

J Neutron:

Please enclose your userChrome.CSS code in tags.

A few things to try:

• Right click anywhere around your back/forward buttons. Toggle the "Menu Bar" setting.
• Try the Default 12.0 theme if you are using a different theme.
• Go through your add-ons one-by-one and disable any that may change toolbar layout, add buttons, etc.