Monday, 27 August 2007 16:46

Five cool open-source sleeper apps

For a computer, software content is king. Programmable computers began the home computer revolution over 20 years ago. The modern revolution is Open Source software, giving immeasurable utility with no cost or risk. Sadly a lot goes under the radar but here are five sleeper apps really worth checking out.


While not new to the world, the GTK+ based diagram creation program called Dia will be new to many people.

In corporations, Microsoft’s Visio application is regalling many. This produces terrific network diagrams, business flow charts, mindmaps and all sorts of other diagrams which can be reduced to the interconnection of graphical blocks. As a presentation tool it’s up there with PowerPoint.

However, Visio costs – which makes sense; it’s a commercial app. But even those who shell out for the full Office 2007 Professional only get a Visio viewer bundled; you have to pay more for the Visio content creator itself.

By contrast, Dia – which openly admits to being inspired by Visio – is free to use, free to modify and free to distribute. Further, as well as Windows, it runs under Linux. Although the latest version is still presented as sub version 1 – namely 0.96.1 – this is a mature and stable product.

Dia’s built-in shape libraries are mostly technology oriented, with E-R and UML diagrams, flowcharts, network hierarchies and related object collections. Additional digital logic and CMOS shapes are also available elsewhere. Although the standard library is less-replete than Visio, this is not a significant burden for two reasons.

Firstly, the package has a well-defined method for importing new shapes, which are defined as XML files using a subset of SVG (a standard for scalable vector graphics), and secondly, the latest version can import VDX files from Visio. (The default Visio file format is .vsd, however Visio allows diagrams to be saved as XML, which creates .vdx files.) All this means that additional shape collections are easily created with a bit of creativity and in time I’d expect to see a larger library available as people submit their own contributions.

Downloads and documentation are all available on a Wiki site which includes the developer’s envisioned roadmap toward version 1.0.

Filelight and PhileSight

Want to know just where your hard disk space has gone? Traditionally, you might search for files larger than a specified size, or you might use a utility which will show the size of folders one level at a time. Both means need effort and digging around to work out just how your disk is divided up.

Here’s where Filelight comes in. This app is deviously simple. Its home page explains it thus: “Filelight creates an interactive map of concentric segmented rings that help visualise disk usage on your computer.” While accurate, it’s the sort of description which may not click until you see a screen shot; check out and you will understand right away. The fundamental design is a multi-levelled pie chart, showing at a glance where the biggest folders, sub-folders, and sub-sub-folders ad nauseam are to be found. The chart is interactive, and clicking on files or folders opens them up for further inspection.

Due to its single-minded purpose, there isn’t much more that can be said about Filelight. In the open source way, however, other developers have been inspired to take the concept further. Philesight is a Filelight clone but instead of running interactively, it resides on a web server. Running on a schedule, the disk is scanned and the usage data stored in a database; this is then rendered as a series of PNG images which are then viewed across the web. An online demo is available, presumably showing the developer’s system.


Another Gnome app, Tomboy, provides easy to use note-taking for all your random thoughts or clipboard pastes. This is no mere notepad; Tomboy goes much, much further by combining its dead-easy data entry with terrific built-in Wiki-like linking.

This means you can organise all your ideas and thoughts as simply as typing a name. Branching is as straightforward as clicking the Link button. You can rename and reorganise all your notes without breaking any of the links.

Tomboy presents a floating, always-visible, panel to ensure it is no further than just a quick click away. This brings up choices to search for existing notes or create new ones. A table of contents lists notes in last-modified date order.

Tomboy is still a work in progress. One of the exciting plans the authors are working on is letting desktop objects be dragged-and-dropped onto notes, with the app working out intelligently what to do with them. At the moment e-mail can be dropped and support for more types of data is in the works.

Additionally, Tomboy has a plugin mechanism allowing unlimited future utility. A rich set of plugins is already available. Some of the best are “Backlinks” to see which notes link to your current note, and, for coders, a Bugzilla plugin that lets Bugzilla URLs be dragged directly from your browser. The bug number is inserted as a link and flagged with a bug icon. Other plugins export notes to HTML, import notes from the commonly-available Sticky Notes applet and other purposes.

Like the other apps described above, Tomboy’s simplicity masks powerful functionality. Its ability to dramatically de-clutter your thoughts with a minimum of expended effort is absolutely worth taking up.


Inkscape is a powerful and convenient drawing tool which has capabilities similar to well-known commercial apps Adobe Illustrator, Corel Draw, Xara X and Freehand. Inkscape’s cheeky slogan is “Draw Freely” which plays on the high price traditionally associated with high-end desktop publishing and design tools.

The key to Inkscape is the scalable vector graphics (SVG) file format – mentioned earlier with reference to Dia. Supported SVG features include text, shapes, paths, markers, transforms, alpha blending and more. Ultimately, Inkscape aim to be fully compliant with the SVG standard. The key advantage of vector graphics is they can be resized to any zoom level – even very large zoom levels – and still appear crisp and sharp. Bitmapped graphics, on the other hand, become blocky and pixellated when resized to higher resolutions. Both have their place; you would not use a vector graphics program to touch up photographs, whereas The GIMP or Photoshop do this admirably.

A variety of vector-based formats can be imported as well as other typical, if “flat”, raster image formats like JPG, PNG and TIFF. The output can be saved as PNG, SVG or other vector formats. Adobe Illustrator files can be both read and produced. A very comprehensive FAQ is available online as is other detailed documentation.

Samples of artwork produced using Inkscape can be seen at DeviantArt as well as several other locations.

Due to its support for standards, Inkscape can exploit the plentiful set of freely redistributable clip art at the Open Clip Art Library.


All this hard graphical work, charting and file space exploring is hard work, so some downtime is well-deserved. This means you can fire up XMoto for a little two-wheeled open-source motocross fun.

XMoto is a challenging 2D platform game with an integral physics engine. You must take care to control your bike’s throttle, braking and attitude across the different environments presented. These environments range from the expected bumpy ride through to roller-coast like stressful trips through psychedelic worlds. You will even find visitors popping up, like the classic Space Invaders.

An enthusiast fan-base has been built-up, thanks to the addition of small, but cool, features like level replays, web-based high-score posting and user-definable levels. Interesting replays can be submitted and posted online for all to see and discuss and many levels downloaded, all rated in terms of perceived difficulty.

Additionally, the XMoto web site includes a Wiki with many helpful documents such as the manual and FAQ but also a guide for good level design with excellent practical tips to enhance visual effects, realism, performance and most importantly pure playability. One downloadable mod converts the game into a skate park trick-performing platform.

You know you can’t play Solitaire for ever; fire up XMoto, put on your helmet and feel the motor hum.

End matter

Commercial software makes good business sense; everyone has to eat. However, we can all be grateful for the altruistic work of talented people worldwide who selflessly contribute quality open source software to the world. And, at the price, we can eat.

Even should you decide the apps listed don’t cut muster, one of the beauties of open source is you’ve had no financial risk by testing them out. Open Source is the ultimate feature-unconstrained, time-unrestricted, nag-less, ad-free trial.

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David M Williams

David has been computing since 1984 where he instantly gravitated to the family Commodore 64. He completed a Bachelor of Computer Science degree from 1990 to 1992, commencing full-time employment as a systems analyst at the end of that year. David subsequently worked as a UNIX Systems Manager, Asia-Pacific technical specialist for an international software company, Business Analyst, IT Manager, and other roles. David has been the Chief Information Officer for national public companies since 2007, delivering IT knowledge and business acumen, seeking to transform the industries within which he works. David is also involved in the user group community, the Australian Computer Society technical advisory boards, and education.





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