Comment 1 for bug 596653

Confirming - more control about the dimensions of a 3D box would be a useful enhancement, especially as snapping (e.g. to grid) is not fully supported (first node does not snap) and doesn't help when using a 2- or 3-point perspective with finite VPs.

Optionally positioning vanishing points numerically (or with added snapping support) would complement the new feature IMHO.