Prism – the 'distraction free browser' currently bubbling away in the Mozilla Labs – takes your favourite websites and turns them into configurable desktop programs. As the line between desktop and online applications begins to blur, Prism gives you a way to create individual shortcuts to the web services you use habitually. Instead of opening in a browser window with back and forward buttons, an address bar and bookmarks, applications have their own frill-free window.

What's more, you can change the look and layout of that window to suit your needs. The only real restriction is that you still have to go online to use them.

Making applications

The pre-release version of Prism (designated 0.9) is available for Mac, Linux and Windows in two versions; a standalone installer and a version that works as an add-on for Firefox. We used release candidate 2 for the practical parts of this article, running on Windows XP.

Using Prism to create apps from websites is very easy. Launch Prism and a dialogue prompts you to enter the URL for the site you want to convert. Alternatively, use the Firefox add-on version, navigate to a site you want to run in Prism then choose 'Convert Website to Application' from the 'Tools' menu. This time the URL is automatically filled in for you.

Let's try this with online image editor Splashup (www.splashup.com). Launch Prism and enter the URL 'www.splashup.com'. In the Name field type 'Splashup Photo Editor'. Immediately below that you have the option to include various browser elements. In this case we'll leave all of them un-ticked except for 'Enable Navigation Keys'. That way, if you get lost in the application you can still go backwards and forwards through the 'site'.

You can also ask Prism to create a shortcut to your application. This is a good idea – as we'll see in a minute. Tick the 'Desktop' box for now.

Click 'OK' and take a look at your desktop. You should see a new icon labelled 'Splashup Photo Editor'. Give it a double-click and the Splashup site is launched in Prism. There are some further menu-based tweaks you can make to the configuration. Click the 'Commands' icon at the bottom right of the window. The 'Tools' menu enables you to make Firefox add-ons available to Prism applications, while 'Print' and 'Page Setup' are self explanatory.

Try clicking the 'Jump straight in' link in the Splashup window. The application launches in a new Prism window – not a new Firefox window. Prism renders pages and parses code just like Firefox, but without the frills. Now, let's take a closer look under the bonnet.

Configuration files

Return to the desktop icon Prism created for your application. Right click on it and choose 'Properties'. You'll see a very long shortcut path for the application. This gives us some crucial clues to how Prism works. The shortcut invokes Prism, which in turn sends a call to configuration data stored in a special 'WebApps' folder. Start Windows Explorer and navigate to the folder 'WebApps'. You should find a directory named 'splashup.photo.editor@prism.app' within. Open it and you'll find a couple of initialisation files.

If you open the file 'webapp.ini' in any text editor, you'll see a set of simple configuration parameters analogous to the choices you made earlier. There are a couple that aren't available through Prism's menu interface too – like the 'sidebar' attribute. Any of the parameters here can be changed. The binary parameters can be set to true or false, and the text strings replaced by anything you choose.

Here's something more intriguing. Select all the files in the 'splashup' folder and hold down [CTRL], then click and drag a copy of those files to your desktop. With the copied files still selected, right-click and choose 'Send to | Compressed (zipped) Folder'. This creates a ZIP file on your desktop. Select and rename the file to 'splashup.webapp'. The file's icon changes to show that it's now associated with Prism. You've just created a 'webapp bundle' – a portable application version of a website converted for Prism. Double-click on the freshly minted icon and Splashup will launch in a new window.