You can undo an action you have taken in the following ways:

1. Select [Edit]-[Undo] from the menu.
2. Press Ctrl+Z
3. Click the "Undo" button on the toolbar

Redo the action

You can redo an action that you have undone in the following ways:

1. Select [Edit]-[Redo] from the menu.
2. Press Ctrl+Y
3. Click the "Redo" button on the toolbar.