The Interclue extension is supposed to give you a preview of links in Firefox before you visit them, saving you mouse-clicks and, with a little luck, allowing you to move quickly between multiple links on the same page. Unfortunately, the determination to monetize the add-on and keep its source code closed results in elaborations that make the basic idea less effective, and its constant pleas for donations make Interclue into nagware. As much as the usefulness of the basic utility, Interclue serves as an object lesson of the difficulties that the decision to go proprietary can take.
Using Interclue is straightforward. When the cursor pauses on a link, Interclue adds one or more 10x10-pixel icons to the right of the link. One of these icons can either be the favicon of the page referenced in the link, or a generic Interclue one. Other icons can be one of a couple of dozen that give information about the link, such as whether it is to an anchor on a page or encrypted, or the type of file that it points to. Or such, at least is the theory -- in practice, all that you might be able to detect without some desperate squinting is that an icon is available. And, if you do see more without much effort, you still have to remember what the extra icons mean. In practice, all you are really like to care about is that a preview is available, so this effort to add value falls a little flat.
Passing the cursor over an Interclue icons produces a small preview of the site that the link leads to. This preview can save time, just as Interclue promises. But the extension can get confused on some sites -- for instance, on Site Meter, it confuses the link that is supposed to lead to a detailed view with a more general page. Even more troublesome, the preview page is often too small to read without scrolling or resizing, so you do not so much save time as swap moving between tabs for scrolling and resizing. In other words, the usefulness of the preview seems hit or miss.
The preview window -- or ClueViewer, as it is called -- stays open as long as the mouse remains inside it. From the preview, you can move to the previous or next link preview -- a feature that is especially useful when reading a search results page, as Intercon is quick to point out. You can also bookmark the link or open it in a new tab, email the link or copy it to your desktop clipboard, change Inteclue options, or report bugs. In addition, should you have a sudden burst of gratitude or generosity, you can use the preview window's icons make a donation to Interclue from the preview window. More practically, you can right-click in the preview to get the usual Firefox content menu that allows you to save an image or a block of highlighted text. Using Interclue, you might be able to research a topic and save notes without ever leaving your starting page, especially if it is a list of search results.
Interclue installs a small icon on the right of the status bar at the bottom of the Firefox. By clicking it, you open a menu that includes a small tutorial on Interclue, as well as items to disable the add-on either generally or for the current browsing session or page.
As with any Firefox add-on, you can configure Interclue from the Tools -> Add-on menu. You can also open the Preferences dialog from the status bar. Preferences include giving more information about your computer so that the add-on can run more efficiently, and setting the speed with which icons and previews display. They end with a credits tab and a donation tab that includes a long rambling plea for money.
The proprietary dilemma
On the Interclue FAQ, the add-on's developers explain that the software is free for downloading, but because they have taken angel capital, they are not in a position to release the code under an open license. They feel guilty enough that the FAQ suggests that, if they make any money, they may invest some of it in open source projects. Meanwhile, they are talking about subscriber services that will allow users to take advantage of affiliate programs whenever they use Interclue.
This position is worth mentioning partly because the lack of a free license will keep some away from Interclue. But it is also worth mentioning because it seems not only unnecessary, but an example of the dilemmas that proprietary software can sometimes lead to. If the developers can give their software away, they could certainly consider dual-licensing for multiple versions of the project.
Even more significantly, the efforts to commercialize only detract from the software itself. The basic idea behind Interclue would make for a handy Web utility, but seems too slight to build a business around. The effort to do so only leads to complications that do nothing to enhance the basic utility, and to pleas for donations that can only annoy. The result is that, if your position on free software doesn't lead you to avoid Interclue, the efforts to monetize it almost certainly will.