In some files, you may find the certain dialog boxes to be missing their respective libraries. These boxes may include the following:
Expression Selection dialog box:
Articulation Selection dialog box:
Chord Suffix Selection dialog box:
These dialog boxes contain libraries of markings and symbols (i.e. dynamics, articulations, etc.) that can be used in the specific document you are working in. If any number of them appears to be empty, they can be loaded into the file you are currently working in by selecting File > Load Library. This allows you to choose from any number of libraries that are available.
For more information on libraries in Finale, please see the following pages from the User Manual: