When the user executes the Edit->Undo command, the system will restore the gradebook to its state before the most recent updating command. An updating command is any action taken in the Grader Tool that leads to an unsaved change in the gradebook. These actions are outlined in Section 2.7.1.3.
The Grader only saves one "previous state". If no updating commands were executed, Undo will be unusable. If the user presses Undo once, it will also become unusable, since there are no more previous states to restore. The current state is saved as a "future state" when the previous state is restored.
Undo does not apply to any File commands described in Section 2.7.1 (as well as Publish Gradebook in Section 2.2.4), text changes in fields that are not reflected in an updating command, or opening/close of dialogs.
The Edit->Redo command does the opposite of Undo. The system will restore the gradebook to its state after the most recent updating command. Like Undo, there is only one future state saved, and if there is no future state to restore, the command is not usable. When a new updating command is executed, the system clears the future state.
The Grader Tool performs Cut, Copy, and Paste commands using a clipboard. The clipboard holds a single text value that was cut or copied from a field and can be pasted into another field.
To execute a Cut or Copy command, the user selects text in a field and selects Edit->Cut or Edit->Copy. Both commands store the text in the clipboard, but Cut will also remove the selected text from the field. The text will remain in the clipboard until another text value is cut/copied or the Grader Tool is closed. If no text is selected, nothing will happen.
To execute a Paste command, the user must place the typing cursor in a field and select Edit->Paste. The text from the clipboard will be placed where the cursor is. If no text was previously cut/copied into the clipboard, nothing will happen.