1D model: Stretch total depth

[kwinkunks]

I don't completely understand the red circle. It seems arbitrarily placed and could cause confusion about its location being somehow significant.

I think it would be better on the lower edge of the lowest layer. Or at the bottom of the scale bar. Then stretch it down to stretch the whole pile in depth. And I think it can be black.

[ben-bougher]

I tried it on the lower corners, but found it frustrating because I would run out of real estate on my laptop screen.
The current setup is supposed to act like a slider, where the ball can be moved between minimum and maximum allowable depths, which keeps the mouse movement contained to the plot so you won't drag off your screen.
If it wasn't intuitive on your first go it won't be for anyone else, so we should figure else out.