The HotBox
Maya’s “HotBox” is a popular menu structure that appears when holding the Spacebar on the keyboard.
It allows quick access to items in the window menu bar such as “File” > “Save as…” or “Edit” > “Delete by type” > “History”, as well as Polygon Modeling and Animation features that are not available in the shelf.
In MARUI, in the default UI layout, the HotBox is located on the left controller, on the “Menu” button (HTC Vive) or “B” Button (Oculus Touch, Valve Knuckles), and is indicated by the following icon:
Here is a video explaining the use of the HotBox:
https://www.youtube.com/watch?v=T8yV59J1lnQ&index=9&list=PLYt4XosVlCmWKxhYrVzBwu8yEXVGm3jwg