Montage is a new tool introduced in Studio version 12. Editing based on Montage Themes is a powerful feature unique to Studio. Each theme consists of a set of matching templates. Use the dropdown list to select the Theme whose templates you want to view.
The templates available for each theme provide slots for your own video, photos, captions and settings. When you create a theme clip from the template (by dragging it to the Movie Window), the Theme Editor opens to accept your customizations. It can be reopened at any later time by double-clicking the clip. Templates give you a fast easy way to craft visually effective sequences that combine your own materials with built-in animations and effects. Each template defines a video or graphic sequence with blanks to be filled in by you.
How to use Montage Themes
There is detailed information on how to use Montage themes in the Studio Help File. Within Studio go to Help -> Help Topics. This will open up the Help file. In the Help file, select the Index tab and search for "Themes". This will display all of the information on Montage Themes. See the image below: