If you have a set of shapes layered atop each other, the send-to-front control will move the selected shape all the way to the back, while the send-to-front control will move a shape to the foreground. It would be better if these controls, or a separate set of controls were added, that would instead move the shape beneath the shape immediately below it (or above it.)
For example, if I begin with a set of colored shapes, which has a green box on top:
And I want to move the green box beneath the yellow box, my instinct is to click the green box and send it back:
However, this isn't what I want. To fix it now, I have to grab, in sequence, the red box, send it back, then the white box and send it back:
This demonstration is simplified, I could've, at the beginning, just grabbed the yellow box and sent it to the front. However, if I have a large number of shapes grouped on top of each other, this solution is lost in the complexity of the diagram. It would be nice to have a more sensitive control, a +1 or -1 control.