In molecular modeling, every action—like building a molecule, tweaking a conformation, or applying a force field—can dramatically change your model. This flexibility is essential, but it comes with a risk: a misclick or unwanted operation may send your system into an unintended state.
The good news? SAMSON provides a helpful solution: a dedicated History system that allows you to undo and redo most of your operations during modeling. For many users, this might seem like a basic feature. However, in molecular simulations and complex design processes, having access to detailed undo/redo actions can be a real time saver—and even a data saver.
What’s Really Happening Behind the Scenes?
Each document in SAMSON has its own history stack—a structured list of reversible operations associated with that particular file. This means that your modeling actions are tracked locally and independently from other documents you may have opened.
You can easily access the History view using:
- Interface > History
- Or use the keyboard shortcut
Ctrl + 3on Windows/Linux orCmd + 3on macOS
Once visible, the History panel presents a chronological list of your operations. Want to revisit a molecular state from a few steps back? Just click directly on the corresponding action in the list. This makes exploration and iteration extremely practical, whether you’re testing out multiple hypotheses or simply experimenting with geometry adjustments.
The Keyboard Shortcuts Every Modeler Should Know
Alongside clicking actions in the panel, you can also use familiar shortcuts:
- Undo:
Ctrl + Z/Cmd + Z - Redo:
Ctrl + Y/Cmd + Y
This is especially useful if you’re in the middle of a build or simulation setup and quickly need to revert (or reapply) an adjustment.
But Be Mindful…
It’s important to note that not all operations are undoable. Some actions—especially those involving irreversible computations or state changes—might not support the undo/redo mechanism. If one of these non-undoable steps occurs in the middle of your workflow, it might block a full rollback of previous actions.
To stay on the safe side, save your document periodically, especially before applying plugins or extensions that might execute non-reversible commands.
Why Bother with This?
The undo/redo system in SAMSON is more than a convenience—it’s a vital productivity feature. For example, when trying multiple ligand poses or editing a protein’s side chain without knowing if the changes will work, being able to step back encourages creative and fearless experimentation. It reduces mental load and helps keep you in a state of flow.
Whether you’re designing a novel molecule or preparing for a simulation run, remember to use the History view as part of your toolkit. It can be your safety net when things don’t go exactly as planned.
To learn more, visit the official documentation page on History: Undo and Redo.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at https://www.samson-connect.net.