Hi Fred
I think I understand what you are trying to do.
Pick the dimensioning tool you wish to use. hover over a point and the logi cursor will pick it up.
Move off the drawing to the point you wish to start your dimensioing from (keeping the logi cursor guide active). click to place
Go back and pick the next point with the logicursor(it can be out of alignment of the 1st point), move back to where you first clicked and the logicursor will pick up that point as well, Slide the cursor back in line with the point off drawing and the word vertex should appear. click again.
I think the dimension will now be how you want it.
Repeat for more dimensions.
I have made a very quick and rough video and uploaded it to Vimeo. Click on the Vimeo link below. (Kids distracted me halfway through)
I think another person asked about this very same point before as well, but I didn't explain it very well.
Please let us know if this is what you are trying to do or something else.
Vimeo link I,m using shark FX V8 which is quite buggy but I am used to it, so its not a big problem. :-)