Porting a Firefox add-on to a Chrome extension

Google recently opened their Chrome extensions gallery for submissions. So I thought I would have a go at creating one. I’ve made three Firefox add-ons so I thought I would convert one of those.
I chose Wolfram Alpha Google as it has the least browser-related code of the three. Nearly all of it is regular Javascript.

Documentation and Set-up of development environment

The first major difference I noticed was in the quality of the documentation. While Chrome’s documentation is not as comprehensive as Firefox’s, it is much more logical and easier to understand for a first time user. The second difference was in the setup of a developer environment. The setup for Chrome is very straightforward, you put a description (manifest) file in one directory and select that directory from within the browser. Then you add JavaScript and CSS files and click reload in the browser to update each time. Compare this with Firefox where you need to use another add-on or mess around in the install directory to setup, change some hidden options, then restart the browser every time you make changes to browser code.

Extension Structure

Firefox requires that you structure your add-on in a particular way. You need to have CSS files in one place, language files in another and there is another file that links them all together. Firefox also has one file that describes the add-on. Chrome’s approach is more flexible. You can arrange the files however you want and all the configuration is done in one setup file, the manifest file.
The Manifest File
Both Chrome and Firefox have a manifest file that describes the extension. In Firefox, how the add-on integrates with the browser is defined in other files. With Chrome you include these details in the manifest file and the whole process is much simpler.

Scope of extension system

With Firefox you can modify basically any part of the browser that you want to. This is great in that it allows for more complex add-ons like Firebug, FireFTP etc. to be built. On the other hand though, most extensions make use of only a small subset of this power.
Chrome’s system limits extensions to a certain number of predefined use cases. Three of the main ones are “Browser Actions” (adds a button to the top toolbar), “Page Actions” (similar to Greasemonkey), and “Themes” (same as Firefox’s themes).

Problems with porting

I ran into quite a few problems while porting.

  1. Removing Firefox specific code– even fairly simple Firefox add-ons can have quite a bit of code specifc to Firefox for handling things like options etc. I needed to remove all of this code. Better structuring of the original add-on would have made this a lot simpler. Chrome makes use of HTML5’s local storage for storing options. Hopefully this will be easy to do in Firefox in the future too.
  2. innerHTML and innerText.
    Trying to set innerHTML was causing an unexplained error. A google search turned up lots of Chromium comits along the lines of “Removing use of innerHTML from example extension”. Another blog recommended using innerText which solved the problem. Not sure what’s going on here.
  3. Cross-site security restrictions
    Chrome’s system allows you to set exceptions for cross-site scripting but the security restrictions still apply to cross-site scripting between frames (the addon uses an iframe). The way to communicate between frames in Chrome is using a new feature of HTML5 called postMessage. I needed to reference the Firefox document for this one and it seems to work fairly well. My only problem was that the iframe has to first receive a message from the main page before it can communicate back but this can be worked around.
  4. Animated PNG’s don’t animate
    Tried to use an animated PNG file as a background image for a button. Unfortunately, Chrome only supports animated GIFs. Small issue but annoying nonetheless.
  5. Sandboxed Scripts
    The cross-site security restrictions also apply to the web page itself. This caused a serious problem as the Wolfram Alpha page attempted to access “parent” (the main page) and caused a JavaScript error. This error then caused the page to not finish loading. As Chrome sandboxes extensions from the website code, it’s not possible to modify the script to fix this. I haven’t solved this problem yet.

Other interesting differences

Chrome extensions are updated automatically in the background and you can restrict updates to certain versions. Firefox does the same but the update process is much more visible. The self-hosted updating system also looks a lot simpler than Firefox’s.


  • Google has created a very nice extension system that is straight-forward to develop for. While not being as powerful as Firefox’s system it should cover a majority of the add-ons out there.
  • The system seems a lot more secure than Firefox’s. By restricting what extensions can do it should limit the effect of many extensions causing the browser to slow down, which is an oft-cited problem with Firefox.
  • Having a simpler environment should make it easier to attract more developers as well. Nearly anything you can do in Chrome can also be done in Firefox so I don’t think we’ll see a huge amount of innovation in the browser experience but we will see a lot more site-specific, Greasemonkey-like extensions.
  • Mozilla’s Jetpack seems to be trying to create an extension environment similar to Chrome’s. Mozilla will likely include this in the browser once it stabilizes some more.
  • One nice thing to look out for is that Chrome extensions can easily support scripts for multiple sites in the one add-on. This should lead to some good “packs” of Greasemonkey-like scripts that change the browser experience across related sites.

As the extension is not working correctly (see Number 5 in Problems with Porting) I haven’t uploaded it to the Extensions Gallery. You can download it from Google Code (the source code is there as well) for the time being.
If anybody could help fix this problem it would be greatly appreciated.

Customize Titlebar Firefox Add-on now public.

I released my 3rd Firefox add-on a while ago. It’s called Customize Titlebar and it’s now been approved by Firefox to be included in their approved public downloads.
Customize Titlebar does basically what it says it does. It lets you change the text that appears in the title of the browser window. You can see this in the screenshot below.

The title now shows the page name, the Firefox version and the URL of the page

The title now shows the page name, the Firefox version and the URL of the page

Why would this be useful?

  1. If you use multiple Firefox profiles it lets you put a name for each profile in the title so you can distinguish which one is which. I have four profiles that I use: a main one, one for testing new add-ons, and two for developing add-ons in. So it’s easy to get them mixed up.
  2. Another use is for web developers and Firefox developers who need to test their pages/applications in multiple versions of Firefox. You can include the Firefox version number right in the title so you know exactly what version you’re looking at.
  3. Another use which seems to be quite popular is for displaying the current URL in the title. This can be useful for people who hide the navigation bar or want to be able to see the URL in the OS taskbar when the window is not open.

The latest version added support for using Unicode characters in the title so hope you find that useful.
Please let me know what you think of it either in the comments or by email on the contact page.

100,000 Downloads of Wolfram Alpha Google

So the download counter for my Firefox add-on Wolfram Alpha Google just ticked over 100,000 downloads. It’s quite an exciting milestone for me and I want to thank everyone who has tried it out and especially those of you who have given feedback and reported bugs.

Wolfram Alpha Google - 100,000 Downloads

Wolfram Alpha Google - 100,000 Downloads

The success of the add-on has mostly followed the interest in Wolfram Alpha itself with the biggest spike when Wolfram Alpha just launched. Every so often though the add-on gets picked up by some blogs and gets a pickup in downloads.
So what happens from here? What I’m planning at the moment is a more general “{any search engine} Google” set of add-ons. There would be one add-on for each engine but when multiple add-ons are installed they would be compatible with each other. If you’ve used Googlepedia and Wolfam Alpha Google together you’ll understand what I mean.

Wolfram Alpha Google And Googlepedia

Basically adding another add-on would add another tab button on the top right of the Google results which lets you switch between the results of any of the engine add-ons that you’ve installed.
I plan to take this one step further and make the rules for how to load and display the results totally generic so that anyone else could write their own add-on that would be compatible with all the others.
My first target for this would most likely be Bing but if you have other ideas for what would work well with Google then please let me know.
I’ve also updated the Wolfam Alpha Google page on this site to be a bit less crappy. Hopefully I’ll find time to fix other parts of this site as well.

Show Adwords Destination URL on Google

Often when I’m looking at the Google results pages (SERPs), I want to be able to see what landing page, click tracking software and advertising agency other advertisers are using. I also want to be able to check that my ads are going to the right page and they are being tracked correctly.
Normally, you need to actually click on the ad to see the landing page. And to see the click tracking software, you need to use a tool like Live HTTP Headers. This can be tedious and you only do it when you really have to.
What I really wanted was to be able to see the destination URL directly and show what advertising agency is running which ad.

So, I came up with two tools that work together to achieve this. One is called Ad Highlighter which changes the link color on any ads that are using click tracking software. The color changes depending on what software they are using. The second tool is called UnMask URLs. When you click this button on a Google search result and mouse over the link, the actual destination URL will appear as shown in the screenshot below.
Both of these tools are included in my free Firefox Addon called SEM Tools which you can download here.

After installing the Addon, try this search result or this one.

Google UK Search Result for "new york flights".

Mousing over the link shows us that Citroen is using DartSearch for tracking.

These tools also work on Yahoo and Baidu. Yahoo and Baidu make it especially hard to show the destination URL but the UnMask tool can still decode these URLs, although it takes a little longer to process.

You can test it on this Yahoo page or this Baidu page. Make sure to click the UnMask URLs button once you get to the page. You don’t need to press the button on Google but it will still work.

Yahoo US - "Las Vegas Hotels" Query

After pressing the "Unmask URLs" button we can see that MGMMirage is using Atlas,

If you would like to add or change which advertisers appear, you can edit the list yourself from the Options menu or just send me an email on the feedback page and I can add it to the next version.

Pay-Per-Click Software Companies

Are you looking to hire a pay-per-click agency? Looking to work in one?
There are really a lot of companies in this industry, so how do you choose the right one?
In online advertising, technology can really give a company an edge so it’s worth understanding which technology the agency you choose is using. Obviously this is not the only thing to look for but it is a good place to start.

To run a pay-per-click campaign it is essential to be able to track when people click on the ad and whether they go on to buy something from your site. What happens after clicking the ad is called post-click tracking and this is the basic technology that all SEM campaigns need.
We can divide companies up into three groups based on the the type of post-click tracking software they use as follows:
1) Search Engine’s own tracking software
2) Third-party tracking software
3) In-house or Proprietary software

1) Search Engine’s own tracking software
Google, Yahoo and Microsoft all provide their own tools and software to track post-click sales. If you have a small site/budget or you work with a small agency then this is a common choice. Google’s system integrates with Google Analytics so this makes implementation easier.


  • Cost– No extra cost for using their software.
  • Integration– The software is integrated with the click data so all the data is in the same place.


  • Compatibility– Difficult to use the same tracking across multiple search engines.
  • Data Ownership– All your data is owned by the same company that is selling you the ads.

2) Third-party tracking software
Companies like Doubleclick (Google owned), Atlas (Microsoft owned) and Clickable (independent) provide access to their software on a self-serve basis. The payment system varies but often it is based on cost-per-click. These systems are popular with cross-media agencies as they are often connected with tracking systems for display advertising.


  • Compatibility– Using the same system across multiple engines is one of the big selling points for these companies.
  • Data Ownership– The data is not owned by the search engines.
  • Added extras– Often you will get advanced features that aren’t supported by all the engines.
  • Cross-media Tracking– Often these systems integrate with tracking software for other media like Display Advertising.


  • Cost– The price might seem low per click but it can add up to a lot. Depending on the price structure this can be a problem in some verticals (low-margin/low CPC industries).

3) In-house or Proprietary software
Many search engine advertising agencies have their own custom tracking software. This can be a differentiator for these companies. Companies with their own proprietary systems are normally pay-per-click specialists.


  • Compatibility– Same as in number 2, using the same system across multiple engines is one of the big selling points for these companies.
  • Added extras– Many agencies will use their technology to differentiate themselves. This can mean access to advanced features, reporting and other value-adds.


  • Data ownership– Changing agencies can be an issue as it means changing tracking software. Re-implementation and transfer of data can be an issue.
  • Cost– Some agencies will charge a separate fee while some will integrate it into their regular fees.

So that gives you an idea of the available options. A lot will depend on the goals of your marketing.
Generally speaking, small companies or companies with low budget campaigns will often go with Number 1.
Companies with a large marketing budget across many media often go with Number 2.
Online companies or companies in verticals where search is very important (travel, classifieds etc.) often go with Number 3.
But again, this won’t suit every company or every agency.

If you are looking for a company with their own proprietary system (Number 3), I’ve put together a List of 3rd-party pay per click tracking software.
If you know of other companies and would like to add them to the list then please let me know on the Feedback page.

Broken Link Checker Firefox Addon

Broken links suck! No matter whether you are a webmaster or a search engine marketer, dealing with broken links can be a huge time sink. So what can we do about it? The following steps will show you the easy way to do it using my free Firefox Addon. If you don’t already have it you can get it here.

1) Firstly, get a list of the URLs that you want to check.
If you are checking links from an adwords campaign, open up Google Adwords Editor, go to the keyword or creative tab and copy all the keywords/creatives and their URLs. If you want to check the links on a website, go to the page with the links you want to check and then choose “Get Links” from the toolbar (it’s in the URL Tools drop-down).Check Broken Links Button

Then click the “Copy all Links” button.

Copy all Links Button

2) Now we’ve got our list, open up the Link Checker.
It’s called “Link Checker” and it’s in the URL Tools menu.

Broken link checker
Then paste the links from step 1 into the top box.
It’s OK if there is other text as well because the Link Checker will just ignore the extra text.
If you are copying the links from Adwords Editor then check the “Is there a header row?” box to ignore the first line.

3) Run the Link Checker.
Click the “Check URLs” button. Below the button you can see the progress. In the bottom box are the results of the test.
If you copy all the results and paste them into a spreadsheet you can see which links are dead or broken and which are working OK.

4) Replace the broken links in your site/ad campaign.

The results also include the “Final URL“. For most links this will be the same as the original link but if you are using click tracking or other URL redirects, this column will show you the actual page that users land on.

Happy link fixing!

What is SEM Tools Pro

SEM Tools is a Firefox add-on that helps you manage Pay-per-click (PPC) campaigns. It’s intended for people who manage PPC campaigns full time (or at least most of their time). I started working on it because I found myself spending a lot of time doing manual, tedious work instead of doing the interesting things like analyzing performance, optimizing campaigns or thinking about new marketing strategies.

Things like checking a campaign for broken links, getting a list of keywords and URLs from a page, sorting keywords into groups and checking Google results pages are tasks that I’ve had to do many times in my SEM career and every time I thought there must be a better way.

Gradually the add-on has grown from a tool to solve one problem (show what tracking tools competitors are using) to solve many, many problems. And all of this is for free. There are still many more problems that I want to solve though. For the last few months I’ve been busy working full-time on solving some of these problems. The problem is that to keep on developing this add-on I need a way to support myself. Since SEM Tools is free I don’t make any money from it. I decided that the best way to keep on offering great tools for free as well as earning enough to support myself is to make SEM Tools into a free-mium product.
Free-mium means that you give away a product for free and then charge for bonus features. It means that the maximum number of people get to benefit from your product but you can also earn some money as well. Other well-known companies with a similar system are Skype and Flickr.

What will this mean for SEM Tools? Firstly, it will still be available for free and you will still get all updates for free. Everything in the current version will continue to be free and I will continue adding new features to the free version. Secondly, there will be one new menu called SEM Tools Pro. This menu will have an option to upgrade to the Pro version as well as features that are available only in the Pro version. Right now, the Pro version has a Creative Writer tool and I’ll be adding more features shortly. You can read about the Creative Writer on this post: How to write effective Adwords creatives. When I add a feature that is more advanced or that takes me a lot of time to make I will most likely add it to the Pro version.

If you want to try out any of the Pro tools you can get a 1 month trial for free. There’s no need to enter any details, you just click the “Try SEM Tools Pro for Free” and it will activate it for one month. After that you will need to subscribe in order to keep on using those features. The price is USD$24.95/year per person and you can use it on as many computers as you want as long as it’s just being used by you. This will include all updates to both the Free and the Pro version. If you want to learn more about what’s included in the Pro version have a look at this page.

How to write effective Adwords creatives

Lately I’ve been working on a creative writing tool for my Firefox add-on called SEM Tools. The tool’s main purpose is as a replacement for using “creative templates” in a spreadsheet. But while making it I also had some good ideas to improve the overall creative writing process.
So first let’s look at what makes a good creative.
A good creative should:
1) Relate to the keyword
2) Have a strong call to action
3) Relate to the landing page
4) Stand out from competing creatives

So how does the creative writing tool help you to cover those four characteristics?

1) Relate to the keyword
First of all you need to know what keywords are in the adgroup. So whenever you select a creative it will show you a list of keywords in that adgroup in the keyword tab at the bottom of the screen.
Secondly you want to use dynamic keyword insertion wherever possible. But dynamic keyword insertion is a waste of time if all your keywords won’t fit in the character length limit. So whenever you select or edit a creative that uses dynamic keyword insertion it not only tells you the length of the default creative but also what percentage of keywords in that adgroup will fit in the character limit. If you only cover a small percentage of keywords I recommend that you either modify the creative to make it shorter or create a second shorter creative.

2) Have a strong call to action
I haven’t worked out how best to help with this one. If you have any ideas I would love to hear them. What I’m thinking of for the future is to have a tab with lists of standard calls to action for different categories to give you some ideas to start with.

3) Relate to the landing page
The first thing to do here is to actually look at the landing page and get a clear idea what it’s all about and what language it uses. So whenever you select a creative the tool will show you the landing page for that creative in a tab at the bottom. Simple but quite effective and saves you copying and pasting it into your browser.

4) Stand out from competing creatives
This is one thing that I think most people don’t do as often as they should. It doesn’t matter how good your creative is, if the competitors creative next to yours is better then it won’t perform well. As an example, say you are advertising credit cards and you include the interest rate in your creative. If the competitor has a significantly better interest rate then your creative likely won’t work very well. In this case you’d be better of emphasizing another feature of the credit card like the interest free period.
To check what your competitors’ creatives look like, just select a creative in the Creative Writer and the Google search results (SERP) for a keyword in that adgroup will automatically appear in the Google tab at the bottom. You can also change the language and country to the appropriate setting and it will remember it the next time as well.

Having all the information you need right at your fingertips can really help in writing better creatives. The one important thing the Creative Writer can’t do is be “creative”. That part is up to you.

If you are interested in being a better Adwords creative writer and you don’t already have SEM Tools you can download it for free from here.
To start using the Creative Writer, go to the “SEM Tools Pro” menu in the toolbar and click “Try SEM Tools Pro for Free”. This will let you use the Creative Writer for free for one month. Then you can open Creative Writer from the same menu.

If you have any questions or suggestions please leave them in the comments or send me an email from the Feedback page.

Google Chrome OS – Yet another take

Since the announcement of Google’s Chrome OS two weeks ago there has been a lot of commentary in the blogosphere and mainstream media.
They cover three important points:
1) Why would Google make an OS
2) Will it be successful
3) What impact will it have

Asa Dotzler from Firefox makes a good summary of what kind of metrics could be regarded as succesful for Chrome OS with the result that wildly successful would still only mean 2% of the total OS market.

The articles I read about why would Google make an OS (TechCrunch, CNet) all seemed to focus on the idea that “More time spent on the web = More money for Google”. While this is true to an extent, it misses a few important qualifications.
Qualification 1: Advertising and in particular online advertising only grows if the advertisers gain more money from increasing their advertising. So people spending more time on the web only equals more money for Google if they also buy more from the advertisers. Otherwise more time on the web (more ad impressions) just leads to lower average CPMs across the whole internet.
Qualification 2: Trying to grow revenue by increasing overall time spent on the web is a very indirect strategy. It would need to have a massive effect on users browsing habits to make a difference which would then be spread out among all sites on the web not just sites with Google ads. Google only has about 30% of the online advertising market so this strategy is pretty far out there from a business perspective. To think of it another way, it’s kind of like an umbrella manufacturer doing cloud-seeding to make it rain more. Doesn’t really make sense.

So what are some more likely reasons for Google’s Chrome OS.

1) Web as a platform
This phrase is thrown around a lot but I don’t think many people fully get what it means and how important it is to Google.
Web as a platform means applications are written in a web standard way (HTML, Javascript and CSS) on the client side and can communicate via HTTP with a server running whatever you want. This is how standard web apps like Gmail etc. work now and more and more applications are being delivered this way. We are also starting to see these kind of apps delivered in new ways. The Prism project from Mozilla takes a web app and gives it it’s own process in the OS just like any other native application but still using web standards. Adobe Air, Palm’s Web OS and Mozilla’s XUL-Runner all also basically give you a way to run a web app like a native application. Chrome OS is basically just taking this idea to it’s logical endpoint. All applications are run as web apps.
The web as a platform is such a powerful idea because it has the potential to really deliver on the “write once, run anywhere” idea with an added bonus of “update automatically”.
It’s important to Google because:
a) they want to reach as many people as possible with their applications (and ads)
b) they want to do this with the least cost possible.
c) they are already very good at doing this and have a strong competitive advantage.
Currently to build a native application that runs on Windows, Mac, Linux, Iphone, Android, Symbian and Windows Mobile takes a massive amount of development effort and cost that even Google struggles with for all but the most popular applications. If you use the web as your platform instead you can already reach all these platforms with almost no changes. And if your application can be run in the same way as native apps on that platform then there is no need for a native app anymore.
How can Google hope to influence the entire OS market to follow their lead? In the web browser market we can already see how browsers with a minority market share can push the market leader to follow standards.
Having an OS built on the same standards would also push the other larger OSes to follow the standards as well. And all web applications would work without any major modification so Google would have a huge development community from the start.

2) Remove reliance on third parties.

A second likely reason for Chrome OS is because currently Google relies on other companies products to deliver it’s own products. The products relevant here are the browser and the OS. Google relies on Mozilla to direct a large amount of traffic to it’s site through the browser search box. But Google has little leverage (other than money) over Mozilla to continue doing this. If some other company offers more money then Mozilla has little incentive to stay with Google. Browser’s implementing their own features rather than standards also hurts Google because it has to adjust all it’s products to support this. These are the reasons Google built the Chrome browser.

So does the same logic apply to the OS? Not as directly as any changes that OS makers make are taken into account by the browsers themselves so Web applications don’t need to deal with them. But Google is thinking beyond just web applications delivered in the browser. It really wants the web standards and APIs that we have in the browser to be the base of all applications. Google wants applications like Gmail to be able to run just like it’s native competitors (Outlook) but with all the advantages of the cloud. I guess Palm’s PreOS is a good example of where Google sees the future of applications.

So is Google’s vision of the future realistic? It’s not unrealistic, and how technology evolves is not just something that happens by itself. The people creating the technology have the control and Google wants to be one of those leaders, not just a follower.

Iframe Buster Buster in a Firefox add-on

I’m the author of a Firefox add-on called Wolfram Alpha Google that shows the results from Wolfram Alpha on the Google search results page whenever you do a search on Google. It worked pretty well up until this Saturday. On Saturday afternoon I came home from the beach and was searching for something on Google when the page suddenly redirected to Wolfram Alpha.

After digging into the problem I found that Wolfram Alpha had added some code commonly referred to as a “frame buster” to their site. This totally broke the add-on so I quickly put together a new version that disabled the add-on and released it on the Firefox Add-on site. On Saturday night Wolfram Alpha had removed the new code and the extension worked as normal again.

Over the last few days I’ve been trying to come up with a proper fix for this and it turns out it’s a lot more difficult than it seems. Basically what I’m trying to achieve is to add a document from one site to another site (in an iframe) and not let the first document have access  to the page that it is added to.

Some of the things that I tried were:

  • An Ajax request and find and replace the code before loading it –> This works and I’ve used it in my other Add-on (SEM Tools) to load Baidu which has the same problem. But it is very easy for the website owner to break this so it’s not a great solution.
  • Using defineGetters (__defineGetter__) –> This DOM method allows you to change the native code that is called when another function accesses the properties of an object. This seems like  the ideal solution but I couldn’t get this to work consistently on the window object’s properties. It would work in  some situation (e.g. with a local file) but then it would be overridden when the window object changed or it wouldn’t work as part of an add-on. I think there must be a way to make this work but I couldn’t figure it out.
  • Replacing the properties on the iframe –> Similar to above but these are mostly read-only so this doesn’t work.
  • Iframe within an iframe –> The inner page can still access the top-most page so again no good.
  • Iframe within an XUL iframe –> The XUL iframe should act as a barrier to stop the internal iframe accessing the outer page but you can’t insert and XUL iframe into a HTML document because of security restrictions.
  • Configurable Security Policies (CAPS) –> These are supposed to give you fine-grained control over what access different websites have, including controlling changing the location on an outer iframe. I couldn’t get this to work though. I’m not sure if this is still part of Firefox anymore.
  • Using object tag instead of iframe –>Objects work  the same as iframes in this situation so no good either.
  • Loading both the Google page and the Wolfram Alpha page in a new XUL browser –> This would work but then the URL bar and the page title would show the wrong name etc.
  • Loading the iframe outside of the page. –>This works!
  • Copying the above iframe into the main document –> This worked to get the content into the main document but it lost all the styling and I couldn’t interact with the page because there was no reference to the document that it belonged to.
  • Loading outside the page and then loading again inside the page –> This works! After all that this was the best solution I could come up with. Basically it won’t load the page if it detects that their is a frame buster being used. You can see the code I used here. However this doesn’t really solve the problem of the access between the documents and it can be worked around too. For example by adding a settimeout to the check for frames code.

One solution to all of this would be to use Wolfram Alpha’s API which I have been thinking about doing. However with the current framework I have, it should be fairly simple to extend it so that it would work with any other website. Using a site-specific API means it will only ever be useful for that one site.

I guess more importantly, why is it so difficult to do something like this? Is including one document in another document without letting them communicate with each other inherently wrong? I don’t think so and in many ways  it is a lot more secure than the current implementation of iframes. I think that mash-ups like this are quite a different use case than just wrapping an entire site in an iframe and loading it on a different domain.

If someone has come up with a better solution than this I would love to hear about it. There are a few use cases I have for this that I would love to have a simple function like loadSafelyInIframe(iframe, targetUrl) for.

So as a result of all this, I added this code to the add-on but disabled it by default as it basically doubles the load time. The Wolfram Alpha page is already very slow compared to Google so I felt that this would make it unusable. If you want to be safe or you notice this problem again you can just check the option in the Options screen. The new version is 0.8 and you can get it here once it’s been reviewed by Firefox.