The two pop-up menus near the lower-right corner of the Viewer let you quickly choose source clips and generators.

This pop-up menu shows recently used clips. A clip is not added to this list when first opened in the Viewer, only when another clip replaces it. The last clip that was replaced in the Viewer appears at the top of the list. By default, the maximum number of clips that appear in this list is ten, but you can change this number. For more information, see Choosing Settings and Preferences.

Use this pop-up menu to create a generator clip, such as bars and tone, text, black, a color matte, or a gradient. A generator clip appears in the Viewer; you can then customize it using the Controls tab. For more information, see Using Generator Clips.
