Hi Gary - for v1 there isn't any way to get a full size readout, but this has been added in for v2, see my other reply here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=2308.10


For v1 you have to draw a line and look at the distance readout to see its length, or there is also a custom "Distance" command that you can get from here:
http://kyticka.webzdarma.cz/3d/moi/#MeasureDistance

The focus in v1 though is much more on drawing something from scratch accurately, and not so much on dealing with imported geometry.

For example there are controls for each drawing tool that let you draw lines of a specific length or angle, when you draw a rectangle you can enter a specific width and height, a specific radius for a circle, etc...

It sounds like you are interested in measuring geometry that is imported from other sources, v1 is not really set up for that task. v2 handles that better with the new size readout, and probably more stuff for that will come in v3.

- Michael