I want to be able to see what the dimension that I am going to place is, before I click and commit to it. One example would be the angle between two lines. You can get the acute, or obtuse angle depending on where you place the dimension. Unfortunately you may not know for sure whiuch dimension that it's going to be until after you place it. Then if it's wrong, you have to delete it and start over. Depending on the size of the area that you need to click on to get the desired dimension (like with a very narrow angle), this can turn into a "find the correct pixel to click" exercise that can get quite frustrating. It would also make many of the menu's where you have to click "horizontal" "vertical" or "slanted" obolete because you could just move until it creates the correct dimension.