Undo and Redo

The ease with which you can manipulate the model using the graphical techniques provided in Design makes the provision of an ‘undo’ facility a natural requirement.

There are three types of activity that are recognized while you are in Model Editor mode. For each of these, the current state is saved before the change in order that it may be restored by a subsequent Undo.

Changes to the database as a result of manipulating the Graphical Selection either by direct graphical manipulation or from the context sensitive menus can be undone. (The selection set and the position/orientation of the Locator Handle are also restored.)

• To undo an activity, do one of the following:

  • Use the standard Undo and Redo icons ( ) in the main toolbar.

  • Use the Undo and Redo options on the Edit pull-down menu.

You may step back through undo states one at a time. Following an undo, you can then choose to redo the sequence, stepping forward one state at a time until the sequence of changes that were undone are restored. If you do one or more "undos" and then save a new state, the redo option is no longer available and the corresponding icons/menu options become inactive.

Switching between applications in Design causes the Modify mode button to be switched off and the undo/redo states to be re-initialized.

Notes: Undo/Redo operations can also take place outside of Model Editor Mode. If the Undo operation involves moving into or out of Model Editing mode, then the switch into that mode happens automatically, and the Model Editor button and menu option will reflect the change. The selection set and handle appropriate to the editing operation that was being used are also restored.

Other ‘undoables’ (operations or sequences of operations that can be undone) can be defined as a PML ‘undoable object’ ‑ refer to Software customization Guide.