Command -click (Mac) | Control -click (Win) the header of a panel to close all panels (hiding all of their options at once). Command -click (Mac) | Control -click (Win) again to display the contents of all panels.
To display the contents of one panel at a time, Control -click (Mac) / right -click (Win) a panel header (excluding the Navigator and Histogram panel), and select Solo Mode. In Solo Mode, clicking one panel header automatically closes the others. This can be especially useful when working on a laptop or smaller display.
Option -click (Mac) | Alt -click (Win) the triangle on the panel header will also enable Solo Mode. The triangle will be a dot pattern while in Solo Mode and solid in the default mode.
Shift -click an additional panel’s header to display the contents of more than one panel while in Solo Mode.