Screen Ruler 4.3 is free, but
unsupported and outdated version.
Help Info - General Notes
The user-interface should be friendly, but who knows... So, here is a quick preview on how it works:
* The ruler is transparent and you can customize the level of transparency
* Use the left mouse button to move the ruler - as usual for all windows programs
* To use vertical and horizontal guides - left click over the respective guide (hides labeled as V Guide and H Guide on the screen shot below)
* To close, change units etc. -- right click over the ruler. Following menu appears:
* The program comes with system-notification area icon (bottom-right corner of the screen) - right-click over the screen ruler icon to open the menu. To put screen-ruler in the notification area (system tray) just click "minimize to tray"...
Since version 1.1 of the Screen Ruler, after a user request, I added "left-click" show/hide functionality -- you can show and hide screen ruler just by clicking with the left mouse button over the screen ruler tray icon
*Mac and Mac OS are trademarks of Apple Inc., registered in the U.S. and other countries.
**Windows is a registered trademark of Microsoft Corporation in the United States and other countries.