By default symbols in all packages are listed, but you can restrict the search to certain packages by clicking the Select Packages... button. This raises a dialog which you use in just the same way as the Profiler's Selected Packages dialog - see Choosing packages for instructions.
When you have selected packages only those symbols whose home package is amongst the selected packages are shown, unless Accessibility (see Accessibility) is set to All , in which case symbols inherited by the selected packages are also shown.