There are several specialized quad menus available when you are working in the Edit UVWs dialog, or when you press any combination of SHIFT, CTRL, or ALT while right-clicking in any standard viewport.
These additional menus provide quick access to tools directly under your cursor. You will find these handy when you work in expert mode, without the command panel visible.
You can create or edit any of these menus from the quad set list in the Quads panel of the Customize User Interface dialog; however, they cannot be deleted.
These are the additional quad menus and their default settings:
CTRL+right-click: Provides several modeling tools that let you create and edit many geometries, including standard primitives and editable geometries.
SHIFT+right-click: Snaps. Provides access to snap options and settings. See Grid and Snap Settings dialog.
ALT+right-click: Keyframe Tools. Provides several animation tools. The default actions let you create position, rotation, and scale keys, as well as open Track View on selected objects and start Wire Parameters.
UVW Unwrap: Appears when you right-click in an Edit UVW dialog. This menu provides quick access to many of the commonly used UVW actions.
SHIFT+ALT+right-click: Empty by default. Use the Quads panel to customize it.
SHIFT+CTRL+right-click: Empty by default. Use the Quads panel to customize it.
SHIFT+CTRL+ALT+right-click: Empty by default. Use the Quads panel to customize this menu.