A misplaced drag, an unexpected structure change, or an edit that goes further than intended can interrupt molecular modeling. The first instinct is often to press Undo repeatedly—but in a document with a mixture of reversible and non-reversible operations, that may not be the safest response.
SAMSON gives each document its own action history. You can use that history to inspect earlier document states and move through undoable actions, rather than relying only on a rapid sequence of keyboard shortcuts. A deliberate pause to check what changed can help you avoid undoing more than you meant to.
Open the history for the document you are editing
Open the History view from Interface > History, or use Ctrl+3 on Windows and Linux, and Cmd+3 on Mac. The history belongs to the current document, so check that you are working in the document whose changes you want to review.
Use history as a checkpoint, not a panic button
When something looks wrong, first identify the point at which the result stopped matching your intention. In the History view, click an action to move through the document’s previous states. This can make it easier to understand which recorded step you want to reverse than pressing a shortcut several times without checking the model.
For a small, recent mistake, use Edit > Undo or the keyboard shortcut: Ctrl+Z on Windows and Linux, or Cmd+Z on Mac. After each undo, inspect the document before continuing. If the change you wanted to restore is visible, stop there.
If you undo too far, use Edit > Redo: Ctrl+Y on Windows and Linux, or Cmd+Y on Mac. You can also use the History view to navigate between available states. Check the model after moving through the history so you can confirm that the structure is in the state you need.
Know the important limitation
Not every operation in SAMSON can be undone. The documentation also warns that when non-undoable operations occur between undoable ones, SAMSON may not be able to undo the operations properly, which can result in data loss. Undo is therefore not a guarantee that every action can be reversed or that a complex sequence can always be restored exactly as expected.
When a result matters, take a moment to inspect it before continuing with more changes. If you are unsure whether a sequence can be safely reversed, avoid repeatedly undoing without checking what each step does. The History view helps you see the available action history, but it cannot make non-undoable operations reversible.
A quick recovery routine
- Pause when the model changes unexpectedly.
- Open the History view and confirm you are working in the intended document.
- Use Undo once, or select an earlier action in the history.
- Inspect the document before making another history change.
- Use Redo if you moved past the state you wanted.
This measured approach is useful during structure editing, building, and movement workflows: it keeps recovery focused on the relevant change while making the limits of undo visible.
For the full explanation of document history, shortcuts, and limitations, see the SAMSON History documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.