The newest ScreenRuler adds mouse tracking, helping you get precise measurements:
This is by far the most requested feature so I’m happy to finally get it done. 🙂 It works for all metrics: pixels, centimeters, inches, picas, points, and percentage.
The arrow keys now move the ruler by 1 pixel, and Shift-ArrowKeys move it by a bigger step, which is the reverse of previous versions. I hope this makes single-pixel adjustment easier to use and more discoverable.
This release also includes a fix for the only known bug and adds the icon made by Jaanos:
After some testing and feedback I’ll update the Ubuntu package.
GNOME Coder 
Too bad that:
* we can’t translate it
* the icon doesn’t fit well in the high contrast themes
I would like to make it translatable. I’ll have to investigate how that is done with a ruby-gnome app, unless you can offer tips.
Why doesn’t the icon fit well? Is it not in the correct Tango style?
I tried to email you, but the email address you left bounces.
Can you get the Debian package updated too?
Yes, after some time to let people test the changes.
I don’t have an email, that’s why it bounces.
Try to change your theme to the high contrast ones and then look at the applications in GNOME menu. Only a couple of them have made icons for these themes. 😦
Good project. Maybe it will make people realise the usefulness of having their X server set up with the proper DPI and maybe put some more pressure on driver developers to actually set the correct value.
Porcolino:
The icon looks quite tangoish to me.
Should be rather simple for anyone interested in drawing a HighContrast-icon. Probably doable in a hour or so. Maybe worth putting a request on http://live.gnome.org/GnomeArt/ArtRequests
Using Ubuntu 8.10
Screen Ruler 0.85
The ruler is not to scale, meaning if I put a “real” ruler up to the screen to compare to the “screen” ruler the “screen” ruler is about 20% shorter!!!
This has been fixed in 0.88, which uses a better method of determining screen DPI, and also lets you configure the setting manually for when the system tells ScreenRuler bad information (which seems common). Please give it a try!
See the related bug report here: https://bugs.launchpad.net/screenruler/+bug/309159