1. Install Stylish and restart Firefox when prompted.
   • https://addons.mozilla.org/firefox/addon/stylish/
2. Open the Add-ons Manager (Ctrl+Shift+A), then the User Styles category.
3. Click the Write New Style button at the top. Paste the following in the text box, give the style a name, then click the Save button.

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
/*
Title: Hide "add as an application for mailto links" notifications
Author: http://forums.mozillazine.org/memberlist.php?mode=viewprofile&u=261941
Tested on: Firefox 28, Firefox 31
*/

notification[value="Protocol Registration: mailto"] {
  display: none !important;
}

If you object to installing Stylish, you can use the userChrome.css file instead. Just make sure the first line in the style only appears once in that file. There are several pitfalls to using this file, which is why I don't recommend it to those who aren't already familiar with it.

• http://kb.mozillazine.org/userChrome.css

Edit: I filed a bug report. If anyone here has the privileges to mark it NEW, please do so. There's already an identical one for Firefox OS that's ASSIGNED, so I think it's perfectly reasonable.

• Bug 998427 - Don't Ask Again option for Add Application (registerProtocolHandler)

Is there any way that doesn't require an addon? getting really sick of having to fix FF's many UI flaws with yet another addon.

As an alternative, you can add the code to the userChrome.css file below the default @namespace line.

• http://kb.mozillazine.org/userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

notification[value="Protocol Registration: mailto"] {
  display: none !important;
}

The customization files userChrome.css (user interface) and userContent.css (websites) are located in the chrome folder in the Firefox profile folder.

• http://kb.mozillazine.org/Editing_configuration

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Director: Show Folder (Linux: Open Director; Mac: Show in Finder)

JMJimmy wrote:

getting really sick of having to fix FF's many UI flaws with yet another addon.

This isn't a flaw in Firefox. The website pops up that prompt. Websites normally provide a link for you to click on to add them as a protocol handler, but Yahoo! Mail automatically pops up the prompt when you load your inbox.

• navigator.registerProtocolHandler - Web API Interfaces | MDN

The flaw is Firefox's as it allows the prompt to be repeated infinitely. Users should never be required to make the same decision twice, regardless of what a website tries to do.

It is probably not Firefox that is doing this by itself, but is done by a Yahoo script that doesn't test or remember that it already has shown this notification.

They can test for this as in shown here:

• https://developer.mozilla.org/Web-based_protocol_handlers

    if (!navigator.isProtocolHandlerRegistered("fake", url)) {
      navigator.registerProtocolHandler("fake", url, "Fake Protocol");
    }

Firefox shouldn't care what 3rd party code is doing, nor should users. Just as the "Remember password" and "Share location" prompts have a "never" option, so should the "add application" prompt (and any other similar ones). That's handled by Firefox and should be reflected in the UI. It's not and as a result a 3rd party addon is required, unfortunately it has the side effect of blocking all prompts of that type instead of ones specific to a site.

JMJimmy,

If it irritates you that much, you can go ahead and file a bug at Bugzilla to see what developers have to say about it.

• 1. Create an account
• 2. File the bug!

Moses,

I've tried that in the past, they just languish.

https://bugzilla.mozilla.org/show_bug.cgi?id=658883 https://bugzilla.mozilla.org/show_bug.cgi?id=801748 https://bugzilla.mozilla.org/show_bug.cgi?id=816140 https://bugzilla.mozilla.org/show_bug.cgi?id=840062 https://bugzilla.mozilla.org/show_bug.cgi?id=884959 https://bugzilla.mozilla.org/show_bug.cgi?id=899718 https://bugzilla.mozilla.org/show_bug.cgi?id=922046 https://bugzilla.mozilla.org/show_bug.cgi?id=360274 https://bugzilla.mozilla.org/show_bug.cgi?id=448628 https://bugzilla.mozilla.org/show_bug.cgi?id=508687 https://bugzilla.mozilla.org/show_bug.cgi?id=816148 https://bugzilla.mozilla.org/show_bug.cgi?id=876693 https://bugzilla.mozilla.org/show_bug.cgi?id=889550 https://bugzilla.mozilla.org/show_bug.cgi?id=899945

Heck, it took nearly 5 years before anything was done about the case sensitive password issue: https://bugzilla.mozilla.org/show_bug.cgi?id=499649

JMJimmy wrote:

The flaw is Firefox's as it allows the prompt to be repeated infinitely.

You should only get the prompt until you click the Add Application button. In my testing, I don't get prompted to add Yahoo as a protocol handler if it's already added.

All the pathetic excuses being made for Firefox.

I do not want to have to find some obscure CSS file and start editing it with the risk that I completely screw up the program, I want an option with a pretty little tick box that say F off and don't bother me again EVER.

I do not want some stupid App either, had enough of bloatware some of which has adware in it.

This is a FIREFOX issue, it is pissing a lot of people off and they should fix it

Oh and about the share my location NEVER option, they clearly do not understand NEVER because to me NEVER means..well NEVER, yet despite saying NEVER share my location and tell sites I do not want to be tracked (basically known as FO and let me get on) I get "this site wants you to share your location".

FedUpWithFirefox wrote:

I want an option with a pretty little tick box that say F off and don't bother me again EVER.

Such an option doesn't exist. That's what the bug report is for. You can click the Add Application button, you can hide the message with the user style, or you can get the message each time you open your Yahoo inbox.

• Bug 998427 - Don't Ask Again option for Add Application (registerProtocolHandler)

FedUpWithFirefox wrote:

I do not want some stupid App either, had enough of bloatware some of which has adware in it.

As I've repeatedly explained, it's not a software application. It's not a program. It's not an add-on. It's not a plug-in. It's just information, a few lines of text that tell Firefox when clicking mailto:user@example.com links, Yahoo is a possible option to handle them.

FedUpWithFirefox wrote:

Oh and about the share my location NEVER option

If you want to disable geolocation ("Location-Aware Browsing"), set geo.enabled to false in about:config.

• http://www.mozilla.org/firefox/geolocation/