Firefox 3.5 provides you an additional way to open new tab. As similar with Internet Explorer 7/8, you can open new tab by clicking on the “+” sign as located at the end of tab bar. You probably don’t like this feature since you are already comfortable with the existing way of adding new tab, such as CTRL + T, double click on the empty tab bar area or right click on the tab bar and select New Tab. If you feel this feature doesn’t benefit much to you and you would like to remove the “+” sign button, you can do it by using simple trick.

To remove the “+” sign button, you need to edit userChrome.css file and different windows OS stores this file at different location. Follow below steps to get this file edited:

1. For Windows 2000/XP, navigate to C:\Documents and Settings\[yourusername]\Application Data\Mozilla\Firefox\Profiles\[profile.default]\chrome. For Windows Vista/7, navigate to C:\Users\[yourusername]\AppData\Roaming\Mozilla\Firefox\Profiles\[profile.default]\chrome. Since Application Data is considered as hidden folder and if you don’t see it, then you need to go to Windows Explorer and click on Tools -> Folder Options, under View tab look for Hidden files and folders, then enable Show hidden files and folders. Alternatively, you can open Application Data folder directly by typing this syntax, “%APPDATA%” (without double quote) at Run and click OK button to open this folder directly.

2. If you have customized Firefox before, then probably you will have an existing userChrome.css file located at this folder, else just create a new file and named it as userChrome.css.

3. Open userChrome.css by using notepad, then add below string to this file. If you already have userChrome.css file created before, just add this string at the bottom of the file and save it.

.tabs-newtab-button {display: none;}

Once you have completed above changes, you need to restart Firefox. After restarting Firefox, you will notice the “+’ sign button has been removed.