if you download one of the builds from graphicall will work - for a while I was not able to figure out how to snap in 3D - being an architect, this feature is a must, but I watched his youtube videos and I have looked on the left hand side where the actions are listed - the shortcut is: ctrl+shift+alt+right click - this works in 3D and if you want to measure distance between two vertices just press this combination - it is working too if vertices belong to different objects, just that you need to have both/all objects selected at the same time - there is an issue with the build that I’m using (testing) as after exiting the ruler addon the other Blender shortcuts doesn’t work anymore …
THIS BUILD FRON FILICISS HAS THOSE ADD-DONS
I know this is and old thread but both the script and the video are gone. I could really use some kind of ruler for the ortho view grid in a 3d window both in 2.49 and 2.5x