Fix Deep/Shallow selection regression

[Keavon]

At some point not that long after @0HyperCube helpfully rebuilt Deep/Shallow Select in 208e907fa4b561f28bc874211a43f4a762777157, it seems to have broken as a result of a regression ().

Deep Select only selects the shallow group, not the deepest layer in the nested groups. Shallow Select's double clicking causes the double-clicked layer to disappear.

Maybe someone can bisect the Git history to find when that occurred (it was observed to be occurring prior to March, so Jan-Feb are the months to look). This would be a good issue for someone to find and fix.