Final Cut Pro X: Transitions browser
The Transitions browser provides access to all the video transitions included with Final Cut Pro.
To open the Transitions browser, do one of the following:
Choose Window > Show in Workspace > Transitions (or press Control-Command-5).
Click the Transitions button in the top-right corner of the timeline.
You can type in the search field at the bottom of the Transitions browser to quickly find the transition you’re looking for.