The four buttons in the action packages panel are equally intuitive. The List Files button lists files in the selected packages. The Remove button removes the selected packages from the list. The Set Prefix button pops up a dialog box where you can specify the installation prefix for the selected packages. And finally, the Engage button causes the packages to actually be installed and/or uninstalled. Note that the Engage button is the only button that operates on all the packages in the list, not just those in the selection.