Show close button on the last tab in Firefox 3.5+

In Firefox versions 3.5 and later the close button is not displayed on the last tab. If you try to close the last tab by pressing Ctrl+W then Firefox closes with the tab. Sometimes, this can be annoying, so here is a simple fix for the problem.

• Open a new tab in Firefox and enter about:config as the URL.
• Click "I'll be careful, I promise!" button to get to the config page.
• Make the following changes in the config page:
  
  
  • browser.tabs.closeButtons = 1
  • browser.tabs.closeWindowWithLastTab = false
• Close Firefox.
• Goto folder %APPDATA%\Mozilla\Firefox\Profiles\xxxxxxxx.default\chrome
  
  
  •  %APPDATA% == C:\Documents and Settings\\Application Data\ folder in Windows XP
  • %APPDATA% == C:\Users\\AppData\Roaming\ folder in Windows Vista and 7
  • More details on where the Firefox Profiles folder is located in different Operating Systems can be found at http://support.mozilla.com/en-us/kb/Profiles
• Open userChrome.css in a text editor such as Notepad++ or Windows Notepad.
• Add the following code to userChrome.css
  
  

  /* Add tab-close-button to last tab*/
  .tabbrowser-tabs[closebuttons="alltabs"] > 
   .tabbrowser-tab > .tab-close-button {
    display: -moz-box !important;
   }
  .tabbrowser-tabs:not([closebuttons="noclose"]):not([closebuttons="closeatend"]) > 
   .tabbrowser-tab[selected="true"] > .tab-close-button {
    display: -moz-box !important;
   }

• Save userChrome.css
• Open Firefox and you should have a close button displayed on the last tab.