Sets a custom cursor for the buffer. If the custom cursor is null, the current cursor is removed, and a cursor is selected automatically by the buffer (depending on whether the cursor is pointing at a clickback). See adjust-cursor for more information about the default selection.
An embedding buffer's custom cursor can override the cursor of an embedded buffer -- even if the embedded buffer has the caret -- if the cursor is specified as an overriding cursor.
Sets the custom cursor for the buffer to cursor. If override? is a true value and cursor is not null, then this cursor overrides cursor settings in embedded buffers.