New Panel Hierarchies

New panels (like the Surface Editor, Render Properties, Scene Editor, Scene/Dope Editor and others) have collapsible hierarchies. Holding down the Ctrl key when clicking the expander arrow will open or close all children, holding down Shift will affect all siblings and holding down the Alt key when clicking a closed hierarchy will open that group and shut others. Holding Alt when there are several hierarchies open will maintain the one clicked on and close the others. All of the modifiers can be combined, they are not mutually exclusive.