Edit: Please ignore this post.

There is an add-on named keyconfig which allows you to do this. It's not hosted on the official add-ons site ("key config" with a space is a completely different add-on), but has a long heritage. More information (156 pages of posts!) here: http://forums.mozillazine.org/viewtopic.php?t=72994

Sorry, I think that reply probably was irrelevant.

I looked at some past discussions here, and it didn't appear there was any built-in setting to change.

What do you want to happen on Ctrl+Click. Just nothing? There may be a way to intercept it with a userscript.

If you are inclined to try a userscript (which runs in the Greasemonkey extension), here's a sample:

// ==UserScript==
// @name        Kill Ctrl-LeftClick
// @namespace   YourNameHere
// @description Block ctrl+left click on all sites
// @include     http*://*
// ==/UserScript==
function killCtrlClick(e){
  if (e.button == 0 && e.ctrlKey){ // left button + ctrl key
    // GM_log("Discarded ctrl+left click on " + location.href);
    e.preventDefault();
    e.stopPropagation();
    return false;
  }
}
document.addEventListener("click", killCtrlClick);

Hi

sorry I dont know how to use this CODE

I REALLY NEED TO DISABLE THIS FEATURE

would u tell me more .....

Hi ashkan.nemo, if you want to try the userscript, here is how:

(1) Install the Greasemonkey add-on: https://addons.mozilla.org/firefox/addon/greasemonkey/

(2) After restarting Firefox, you should find a monkey icon on your Add-ons Bar or Navigation Toolbar. Or you can use the classic Tools menu (press Alt+t to display it if you are using the orange Firefox button and abbreviated menus).

Choose New User Script and give it any name you like and click the OK button. Your new script (which will be mostly blank) will display in a text editor, or you might need to choose a text editor first (e.g., Windows Wordpad) and then it will display. Replace the contents of that script with the one above, and save it. Then load a page on which you want to test the script and see whether it works.