Anyone who's worked with Flash symbols for any length of time knows how your library can get out of control. Hundreds of symbols, which you try to organize into separate libraries - only to have the annoyance of constantly switching between libraries in your display window, not to mention switching to the default libraries that come with the program. You can make your life a little easier by opening several library panels, and using each one to display the contents of a separate library.
To do this, just click the "New library panel" button in the upper right hand corner of the default library panel, just to the right of the dropdown listing the library name. A new window will open in the center of the workspace; you can drag or dock it anywhere you need to.