Undo

Undo
RnaViz buffers most of your actions. The undo function allows you to return your drawing to the state before your last action, or before that, or ...
RnaViz buffers a given amount of undo steps. This amount can be set in the "Undo steps" item of the "Edit" menu. Some actions (e.g. loading or deleting a structure) cannot be undone, and empty the undo buffer.
Redo
If you have gone too far with undoing actions, you can use redo to redo these actions.
Clear undo
The undo buffer can be emptied by invoking the "Clear undo" entry in the "Edit" menu.