perhaps you should ask @julien_roger for the real-world application of this problem. I’m just making things up to find a case where the workaround doesn’t work…
In the attached, I’ve put some constraints on the system.
Dim-IntersectionPoint.3dm (52.5 KB)
Let’s say that the start point and the y-value of the end point of the black line is correct but the x-value needs to be on the border line on the right.
By 1D scaling from the start point, you can easily snap to the end point for second entry and the border line for third entry into the command. This will make the intersection with the red line move and the dimension will be left hanging.
If you scale from the intersection as you suggest, the dimension will change correctly but the start point of the black curve will be wrong: