NRuler is a transparent screen ruler, used for measuring pixel lengths. It runs on the .NET platform, on Microsoft Windows and GNU/Linux (using Mono).
NRuler is free software, distributed under the GNU General Public License.
NRuler requires at least version 1.1 of the Microsoft .NET Framework. Version 2.0 or better is recommended.
NRuler requires the Mono platform. Version 2.0 or better is recommended. For transparency support, you will need a desktop that supports transparency, such as Compiz.
Questions, problems, suggestions, bug reports, and so on can be posted at the online forum.