Anyone who works with molecular modeling software knows this feeling: you just adjusted a conformation, or deleted a node, or modified a complex interaction… and instantly wish you hadn’t. Modeling mistakes happen to everyone — sometimes it’s a misclick, sometimes a hasty decision, or sometimes the side effect of a change is unexpected.
That’s where the Undo and Redo functions in SAMSON come in. These features aren’t just simple conveniences — they are essential workflow tools that help you explore fearless modeling, iterate designs, and test out ideas without constantly worrying about losing data or accidentally breaking a structure.
How does it work?
In SAMSON, each document has its own dedicated history. That means all the actions you perform — from editing atoms and residues to transforming structures — are recorded in a timeline that you can navigate at any time.
You can access this timeline by opening the History view:
- Interface > History
- Or use the shortcut: Ctrl + 3 (on Windows and Linux) or Cmd + 3 (on macOS)
This graphical history allows you to click and jump to earlier states of the document. You can also step back and forward using the common commands in the Edit menu:
- Undo: Ctrl + Z / Cmd + Z
- Redo: Ctrl + Y / Cmd + Y
Why is this useful?
Molecular modeling is inherently experimental. You’re twisting and refining hypotheses, often transforming complex 3D structures. The cost of error is higher than in a document editor — one wrong move can mean hours of lost progress.
SAMSON’s history system allows you to:
- Confidently try changes without panicking about mistakes
- Move between different modeling states and compare their effects
- Quickly recover from errors or accidental deletions
- Track modeling steps as a form of lightweight documentation
A handy bonus: since history is per-document, you can manage multiple modeling projects in parallel, each with its own undo/redo context.
Here’s a quick animation showing how you can step through your document’s history:
What are the limits?
While many operations in SAMSON are undoable, some are not. If you mix undoable and non-undoable actions in your workflow, it may not be possible to cleanly return to past states. In such cases, you might encounter partial rollbacks or data loss. The documentation highlights these cases, so understanding what can and can’t be undone is important.
In practice
Whether you’re designing a novel molecule, adjusting a protein-ligand complex, or simply reorganizing the structure tree, Undo and Redo make safe exploration possible. It’s especially helpful during educational or collaborative settings, where trying different strategies side-by-side becomes part of the learning journey.
To learn more, check out the documentation on SAMSON’s history system: https://documentation.samson-connect.net/users/latest/history/
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download it at https://www.samson-connect.net.