A misplaced move, an unwanted edit, or an experimental transformation can interrupt molecular modeling at exactly the wrong moment. The first instinct may be to repeat the work from memory. But in SAMSON, your document keeps a history of undoable actions, so it may be possible to return to an earlier state instead.
The important detail is that history belongs to each document. If you are working with more than one document, check that you are viewing the history for the one you intend to change. To open the History view, choose Interface > History, or use Ctrl+3 on Windows or Linux and Cmd+3 on Mac.
Move through states, not just single edits
Undo and redo are useful for stepping backward and forward through document changes. You can also click actions in the History view to move between previous document states. That can be more informative than pressing Undo repeatedly: the list gives you a way to inspect the sequence of actions and choose a point to revisit.
For a quick correction, use the Edit menu or the keyboard shortcuts:
- Undo: Ctrl+Z on Windows and Linux; Cmd+Z on Mac.
- Redo: Ctrl+Y on Windows and Linux; Cmd+Y on Mac.
Redo is useful when you have undone one step too many and want to restore the change. As you move through the history, pay attention to the document state you want to recover—not only to how many times you pressed a shortcut. This is especially helpful when you have been editing, building, or moving structures and several changes have happened in sequence.
One limit to keep in mind
Not every operation can be undone. The documentation warns that if non-undoable operations occur between undoable ones, SAMSON may not be able to reverse the sequence properly, and data loss may result. In other words, undo is a useful recovery tool, but it is not a guarantee that every action can be safely reversed.
A practical approach is to use history as soon as you notice an unwanted change. Open the History view, review the available actions, and move back carefully. If the result is not what you expected, redo can help you move forward again. Avoid assuming that a long chain of actions will always be reversible, particularly when you are unsure whether all the operations involved support undo.
A small habit that saves attention
When trying a transformation or editing a structure, take a moment after a meaningful change to check the result. If something goes wrong, use the history to identify where the document diverged from the state you wanted. This is often easier than trying to reconstruct every intermediate step from memory. The history is per document, and clicking an action lets you navigate among its recorded states; it is not a substitute for caution around operations that cannot be undone.
For the full explanation of the History view and undo/redo behavior, see the SAMSON History documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.