Undo Redo

The Undo command undoes editor operations. The Redo command cancels the last undo operation and restores the state before Undo.
 * The Undo/Redo functions can be called either via the arrow buttons in the main menue or by the CTRL-z for Undo and CTRL-y keys for Redo.
 * Any editor function that modifies the static model can be undone, such as for example adding and removing objects, selecting single or multiple objects, moving objects, and so on.
 * Undo/Redo refers exclusively to the static model. The dynamic model, i.e. the movement of impulses by the model, is not affected.
 * Zoom and mouse operations on the entire model are not saved and cannot be undone with Undo. They do not change the static model itself, but only the representation of the model.
 * The Undo/Redo memory is deleted when a new model is created and when a model is opened. For example it is not possible to go back to the previously loaded model with Undo, after opening a new model. The command "Open model" has to be used for this purpose.
 * The number of operations that can be undone is limited only by the available memory space. For each editor operation, certain data must be stored to enable an undo. Therefore, memory consumption increases continuously while working with the editor. In practice, no problems have been observed so far. If there is a noticeable slowdown in the reaction in the future with very large models and prolonged uninterrupted work with the editor, it is recommended that you save and reopen the model from time to time. This sets back the undo stack and frees memory.