Add a marking menu to the hotbox

User Guide > General > Basics > Preferences and customization > Customize marking menus and the hotbox >

Marking menus appear in the hotbox when you point above (north), below (south), left (west), or right (east) of the hotbox menus and press a mouse button.

You can set each mouse button press (left, middle, or right) in each different area (north, south, east, or west) to show one of the pre-made marking menus that come with Maya, or a custom marking menu you have created.

To assign a marking menu to a hotbox area and mouse button

Select Window > Settings/Preferences > Marking Menu Editor.
Click the marking menu in the list.
Set the Use Marking Menu In option to Hotbox.
Set the Hotbox Region option to the part of the hotbox (North, West, Center, East, or South) where the marking menu appears.
Set the Mouse Button(s) option to the mouse buttons (Left, Middle, and/or Right) you must hold for the marking menu to appear.
For example, if you set the region to South and turn on Middle and Right, the marking menu appears when you show the hotbox (hold the space bar), move the mouse pointer below the menus, and press the middle and right mouse buttons.
Click Apply Settings.