A small change to a molecular structure can have a big effect on the model you are trying to build. Maybe you moved an object too far, changed a structure while testing an idea, or simply want to compare the current document with an earlier state. In those moments, the key question is not just “How do I undo?”—it is “How can I move back through my work without assuming every action can be reversed?”
SAMSON keeps a separate action history for each document. The History view lets you inspect that sequence and move between document states. This can make experimentation easier: instead of relying only on memory, you can look at the recorded actions and return to an earlier point in the document’s history.
Open the history before you need it
You can open the History view from Interface > History. The shortcut is Ctrl+3 on Windows and Linux, or Cmd+3 on Mac. Knowing where the view is before a complicated editing session saves time when you want to check what happened or return to a previous state.
Once it is open, you can move through document states by clicking actions in the History view. You can also use the commands in the Edit menu. For a quick correction, use Undo: Ctrl+Z on Windows and Linux, or Cmd+Z on Mac. To move forward again, use Redo: Ctrl+Y or Cmd+Y, respectively.
A practical rhythm for testing changes
- Make one change at a time when you are troubleshooting. If a result is unexpected, a short sequence of actions is easier to inspect than a long series of unrelated edits.
- Check the History view when you are unsure what changed. Use the listed actions to orient yourself, then select an earlier action to move back through the document’s states.
- Use undo and redo deliberately. Undo can help you test whether a recent change caused a problem; redo can return you to the later state. If you are making consequential edits, save your work regularly as an additional precaution.
- Do not treat every operation as reversible. SAMSON’s documentation warns that some operations cannot be undone. If a non-undoable operation occurs between undoable actions, SAMSON may not be able to undo the sequence properly, which can result in data loss.
That last point matters most. The History view is useful, but it is not a guarantee that every operation can be rolled back. If you are about to try a change you cannot easily reconstruct, take care to preserve your work first. And if undo does not produce the result you expected, avoid repeating undo automatically: inspect the current state and the history before proceeding.
This approach is useful whether you are editing, building, or moving structures: make changes thoughtfully, use the history to understand the path you took, and remember that reversibility has limits. For the complete instructions and shortcut details, see the SAMSON History: Undo and redo documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.