...Originally the program was conceived to assess the angle between north and a given point on any map open on the screen, therefore the background of the application window is transparent and the angle is measured from the positive y-axis and clockwise. The application allows to move the origin of reference axes and to rotate the axes as needed.
OnScreenProtractor works correctly only in Windows context.
In linux 'OnScreenProtractor_v0.6.exe' can be started with 'Wine'