A click in the 3D view selects what you aim at
In earlier previews, a click selected nothing if the mouse moved even one pixel between press and release, a slightly diagonal click turned the view instead, and most of a rack selected nothing when clicked. A click now counts while the mouse stays within 3 pixels of where you pressed, and anywhere on a rack selects it. Ctrl-click and the right-click menu work the same way. A rack in a row still selects its whole row, unless it is set to be selected on its own.