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Undo: Reverses the last action. Mudbox stores an unlimited undo queue without consuming memory (RAM).

Note
The Undo history is not saved when switching between subdivision levels.
Redo: Reverses the last Undo.
Duplicate: Duplicates the selected object. See also Duplicate a model.

Duplicating a mesh also duplicates subdivision levels and any sculpt layers, and any UV values are preserved. If the duplicated mesh is set up for PTEX painting, the new mesh is also set up for PTEX.
Delete Selected: Deletes the selected item, removing it from the scene.
Select All: Selects all objects in the scene.
Invert Selection: Selects all objects not currently selected and deselects all selected objects.
Deselect All: Clears the current selection so that nothing is selected.
Grow Selection: Expands the selection of faces across the surface.
Select Border: Selects the border edges of an open mesh.
Lock Selected: Locks selected meshes. Locked meshes cannot be edited with the sculpting tools.
Invert Locked: Locks all unlocked meshes and unlocks all locked meshes.
Unlock All: Unlocks all locked meshes.
Freeze Selected: Freezes the vertices of all selected faces. Frozen vertices cannot be edited with the sculpting tools. Freeze maps can be painted with the Freeze brush.
Invert Freeze: Freezes any vertices not frozen and unfreezes all frozen vertices.
Unfreeze All: Unfreezes all frozen vertices.
Edit Stencil: Opens the Edit this stencil window. See Edit a stencil.