The Mysterious Grey Box On Gmail

Last week we received an email from an eagle-eyed Gmail user pointing out a strange graphic that has appeared in the top-left hand corner of the application. The icon is a ten by ten pixel graphic with a diagonal line across it, with one half in black and the other in gray. It isn’t an inline image, as you can not highlite it or select it in your browser, nor right-click on it. There is also no reference to the image within the style sheet for Gmail.

All users of Firefox should be able to see the box on both Mac and Windows, and we tested across multiple versions of both the browser and operating systems.

In Firefox:

To add a strange twist, when viewed in Safari the graphic is slightly different – with only half of it loading and the colors being inverted (although it is the same dimensions as what is seen in Firefox).

In Safari:

Gmail is difficult to debug on the client-side because Gmail is written using the Google Web Toolkit, which outputs Javascript and CSS that isn’t really intended for human consumption (have a look at the CSS class names, or just the source to the main page itself as examples). There also isn’t a seperate HTTP request to an image that looks like the graphic that is displayed. When you load the DOM inspector, it shows that the graphic is being displayed inside of an IFRAME, and that frame contains some Javascript and simple XHTML.

Initially we suspected that the graphic may be rendered in SVG, a format that defines vector graphics in XML markup. The theory would be that Google is testing browser compatability for SVG across their user base – although there is no reason why they would run such a test for weeks. Google could be looking to develop a more advanced web interface for their applications in the future using SVG (considering they are squeezed between Flash and Silverlight at the moment).

There was a similar issue reported on a forum back in January of this year, and then it also specifically applied to Gmail (although it was a slightly different issue – see screenshot). This same issue was also recently covered and commented on at Google Blogoscoped. We contacted Google about this back on Wednesday, and we have only been told that they are getting back to us at some point with an official response.