A misplaced click or an unexpected transformation can leave a molecular structure looking very different from what you intended. The first instinct is often to press Undo repeatedly. But when a document contains a mix of reversible and non-reversible operations, blindly stepping backward may not be the safest way to recover.
SAMSON gives each document its own action history. You can use that history to inspect earlier document states and move between recorded actions. A few deliberate steps can help you understand what changed before you try to fix it.
Open the history before guessing
Open the History view through Interface > History. You can also use Ctrl+3 on Windows or Linux, or Cmd+3 on Mac. The view lists undoable actions for the current document, giving you a place to review the sequence rather than relying on memory.
This is especially useful after a chain of edits: for example, when you have built part of a molecule, moved structures, and then noticed that something no longer looks right. Instead of immediately repeating the same action or undoing several steps at once, look at the history and identify the point where the result began to differ from your intention.
Move back in small, observable steps
You can navigate through document states by clicking actions in the History view. You can also use the commands in the Edit menu:
- Undo: Ctrl+Z on Windows or Linux; Cmd+Z on Mac.
- Redo: Ctrl+Y on Windows or Linux; Cmd+Y on Mac.
A practical recovery habit is to undo one step, then inspect the structure before continuing. If that step was not the one you wanted to reverse, redo it and examine the surrounding actions in the history. This makes it easier to connect a visible change in the model with the operation that produced it.
The same approach is useful when experimenting with transformations or constructing a molecule. Treat Undo and Redo as tools for controlled exploration: change one thing, observe the result, and use the history to retrace your steps when needed. The animated example below shows movement through document history.
Know the limit of undo
History is helpful, but it is not a guarantee that every operation can be reversed. SAMSON documentation notes that some operations are not undoable. If a non-undoable operation occurs between undoable ones, SAMSON may not be able to reverse the surrounding actions properly, which can result in data loss.
For work that would be difficult to recreate, consider making a separate saved copy before trying a risky sequence of edits. This is a general precaution, not a replacement for the History view: the history helps you inspect and navigate recorded actions, while a separate copy gives you another point of protection if an operation cannot be undone.
In short: open the history when a result surprises you, step backward deliberately, and check the model after each change. If the operation may be difficult to repeat, protect your work before experimenting.
Read the SAMSON documentation on History: Undo and redo to learn more.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.