I'm imagining two possible behaviors, not mutually exclusive:
An menu option "swap with..." which when active puts the shell into "pick mode", when something is selected it will swap the widgets between the cells. (One of the widgets may be empty)
A blessed active cell, e.g. the one in front of the camera. A menu option for non-active cells to "focus" which sends the current focused widget back to its original cell, and brings the newly focused widget to the active cell.
I'm imagining two possible behaviors, not mutually exclusive: