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Ever have a window which has so much text in it that the vertical scrollbar moves too coarsely to allow you to find the position you want? Like you have an entire dictionary loaded as a text file and you're trying to find the word "madrigal". You get to "machine" and (after some fiddling with the mouse) manage to move the scroller one pixel down only to find that you have overshot all the way to "magical". Then you have to scroll all the way back up to madrigal or go back to machine and scroll down. Either of which, depending on the size of the dictionary, may take quite some time. Most annoying.

Wouldn't it be good if, for long documents like this, you had two scrollbars side-by-side. These would work like the hour hand and minute hand on a clock. The rightmost one would set the position in the document coarsely and the leftmost one would be for fine-tuning it. Once you had got to the "early Ms" with the rightmost scrollbar you could quickly get to any nearby word with the leftmost one.

For best distribution of precision between the scrollbars, the region of the document corresponding to the entirety of the leftmost scrollbar (X) would be to the entirety of the document as the window would be to X (i.e. the pixel size of the two scrollers would be the same).

The scrollbars would be set up so that moving the scroller of the leftmost scrollbar one pixel scrolled the document by at most one line. If the document is too large, than a new scrollbar is added - particularly long documents might have 3 or even more scrollbars, each with the same virtual document size to virtual window size ratio.

One problem I'm always wrestling with while programming is how to see as much as possible of my program on screen at once. I tend to use a very high screen resolution (1600x1200 usually) and a very small font in my text editor (6x8) to see a large quantity of text at once. My coworkers despair that they can never read what's on my screen and say that I must have very good eyesight (I do at short distance - reading road signs while driving is another matter). But even 150 lines is not enough sometimes.

A while ago I had an idea for effectively increasing the number of lines even further. Vertically "compress" the lines that are further away from the cursor, while showing the closer lines at normal size. The further lines wouldn't be legible (unless the document is quite small) but you can see the overall "shape" of the document and easily navigate to different sections. The effect would be kind of like squashing the document vertically so that the whole thing fits on the screen and then looking at part of it with a horizontal bar magnifier centred on the cursor (although it would be a magnifier with an extended cross section so that even lines of text quite far away from the center were magnified a little bit, and there would be no obvious boundary between magnified and non-magnified text). Because of the similarity to a bar magnifier, and by analogy with the concept of a "folding editor" I call this idea the "lensing editor".

Here's an interesting idea I had a while ago. It involves using the microphone in a headset like this, a fixed set of speakers and a high-resolution sound card (like almost any modern sound card) to track the position of the head of the person wearing the headset.

The software works by sending sounds through the speakers and trying to pick them up through the microphone. Once it manages to synchronize the sent pulses with the received pulses it can calculate the exact delay from sending a pulse to receiving it. Part of this delay will be due to the hardware involved or the latencies in the operating system, but these delays should be fixed. The remainder of the time is caused by the finite speed of sound in the medium between the speaker and the microphone. To a fairly good approximation this speed will be constant (about 300m/s) so using the delay one can work out the distance between the microphone and the speaker. Do this for two speakers and you can triangulate the position to a circle in the plane normal to the line between the speakers. Two more speakers and you can determine the position of the user's head quite precisely, up to the resolution limit of the soundcard (most modern soundcards can do 192k samples/second, giving a positioning accuracy of about 1.6mm).

Why would you want to do this? Well, the position of the user's head is a particularly interesting datum because it can be used to move windows around giving a pseudo-3D view. Suppose you have two windows on the screen and one is partially covering another. Normally to see the hidden part of the lower window you have to use the mouse (or worse, the keyboard) to move the upper window or bring the lower window to the foreground. But with a pseudo-3D view each window has a "Z-position" in front of or behind the plane of the monitor. If the user's head moves left then the closer windows move right and the further windows move left, allowing you to "see around" the upper window by moving your head, just as you would do with real objects. I haven't tried it yet, but I think it would be quite effective, and a cheap way to make a user interface much more immersive. I thought of doing this years ago but with an infra-red gadget strapped to the forehead - it only recently occurred to me that this could be done less intrusively with the microphone that many people wear anyway for telephony purposes.