A Ruler for Windows is a simple utility that enables you to measure distances on your desktop. The application provides you with useful instructions, allows you to customize the appearance of the virtual ruler, and offers you options to easily magnify any area from your screen.
This program might come in handy to graphic designers who need to measure distances between two points from their desktops. You can adjust the length of the ruler, toggle between horizontal or vertical mode when needed, and move the main screen anywhere on your desktop.
However, the application comes with various disadvantages. For instance, you cannot rotate the ruler at any angle you like. Many tools of its kind provide you with feature.
Another thing that bothers me is that it supports only one measuring unit (pixels). Also, it lacks an option to hide the main window (ruler) from your desktop. The interface of the tool stays on top of other running apps. The only solution to hide it from you screen is to close A Ruler for Windows.
In conclusion, I'd say you should look for a different app to measure distances on your screen. There are plenty of on-screen measuring tools that provide you with more features and come without price tags.