Ketcher Undo/Redo Bug: Partial Selection Restored

Hey guys! We've got a quirky bug to dive into today in Ketcher, specifically related to the Undo/Redo functionality when you're playing around with the Monomer Creation Wizard. It's one of those things that can make you scratch your head, so let's break it down and see what's going on.

The Problem: Partial Selection Restoration

The core issue revolves around what happens after you enter the Monomer Creation Wizard and then decide to bail out without actually creating a monomer. You'd expect the canvas to just revert to its previous state, right? Well, not quite. Pressing the Undo or Redo buttons can lead to some unexpected behavior, where parts of the structure you had selected for the wizard are shown or restored inconsistently. It's like the ghost of your selection is haunting the canvas, even though you didn't commit any changes. This can be super confusing, especially when you're trying to keep your chemical structures organized and clean.

Why This Matters

• User Experience: Imagine you're working on a complex molecule and suddenly parts of your previous selection pop back up. It's jarring and disrupts your workflow.
• Data Integrity: While it doesn't seem to corrupt the core structure, it gives the impression that something has been altered, which can lead to mistakes if you're not careful.
• Trust in the Tool: If the Undo/Redo functions don't work as expected, it erodes confidence in the software's reliability.

Steps to Reproduce

Okay, let's get our hands dirty and see how to make this bug appear. Follow these steps, and you should be able to recreate the issue:

1. Draw a Structure: Start by drawing a structure on the canvas. A simple cyclohexane ring works perfectly for this.
2. Select a Part: Select a valid portion of the structure. This is the part you'd hypothetically use for monomer creation.
3. Open the Wizard: Fire up the Monomer Creation Wizard.
4. Close Without Creating: This is the key step: close the wizard without actually creating a monomer. Just exit out.
5. Undo/Redo Time: Now, press the Undo and Redo buttons a few times. Watch closely!

What You'll See (Actual Behavior)

You'll likely notice that the Undo/Redo actions reveal parts of the previously selected structure. It's as if these parts were added or removed, even though you didn't finalize any changes in the wizard. This inconsistent restoration is the heart of the bug.

What Should Happen (Expected Behavior)

Ideally, Undo/Redo should restore the canvas to the exact state it was in before you opened the Monomer Creation Wizard. No ghostly selections, no unexpected additions or removals – just a clean reversion to the previous state. This predictability is crucial for a smooth user experience.

Deep Dive into the Technical Details

The root cause of this bug likely lies in how Ketcher handles the state management during the Monomer Creation Wizard process. When you open the wizard, the application probably creates a temporary snapshot of the current structure and selection. If you cancel the wizard, this snapshot should be discarded, and the canvas should revert to the previous state.

However, it seems that the Undo/Redo stack isn't correctly updated when the wizard is cancelled. The application might be partially applying the changes associated with the wizard, leading to the inconsistent restoration of the selected parts. This could be due to issues in:

• State Management: The way Ketcher tracks and reverts changes.
• Event Handling: How the application responds to the cancellation of the wizard.
• Undo/Redo Stack Implementation: The mechanics of pushing and popping states from the stack.

To fix this, the developers need to carefully examine the code related to state management and the Undo/Redo functionality, especially within the context of the Monomer Creation Wizard. Debugging this kind of issue often involves stepping through the code, inspecting the state of variables, and identifying where the discrepancy occurs.

Real-World Impact and Use Cases

Now, let's think about how this bug affects real users and their workflows. Imagine a researcher using Ketcher to design a novel polymer. They meticulously draw a complex monomer structure and then decide to tweak it using the Monomer Creation Wizard. If they cancel the wizard and the Undo/Redo breaks, it can lead to:

• Wasted Time: The researcher might have to manually revert the changes, which can be time-consuming and frustrating.
• Potential Errors: The partial restoration of the selection could introduce unintended modifications to the structure.
• Decreased Productivity: The unexpected behavior disrupts the researcher's flow and makes the design process less efficient.

In educational settings, students learning to draw chemical structures might find this bug particularly confusing. It can undermine their understanding of how the software works and make the learning process more challenging. Therefore, addressing this bug is essential for ensuring that Ketcher remains a reliable and user-friendly tool for both research and education.

The Evidence: Video Proof

To really drive the point home, there's a video showcasing the bug in action:

https://github.com/user-attachments/assets/97215e60-8916-4ee9-92f3-8f7a4e6239d4

Watching the video makes the issue crystal clear. You can see how the Undo/Redo functions don't quite do what you'd expect after cancelling out of the Monomer Creation Wizard.

System Details

For those of you who are technically inclined, here are the specifics of the system where this bug was observed:

• OS: Windows 11
• Browser: Chrome Version 138.0.7204.101 (Official Build) (64-bit)
• Ketcher Version: 3.7.0-rc.1
• Indigo Version: 1.35.0-rc.1

This information helps the developers pinpoint if the bug is specific to certain environments or versions of the software.

The Bigger Picture: Bug Found During Testing

It's worth noting that this bug was discovered during testing for this issue: https://github.com/epam/ketcher/issues/6552. This highlights the importance of thorough testing in software development. Catching bugs early in the process saves time and resources, and ensures a better experience for users.

Let's Wrap It Up

So, there you have it – a deep dive into the Undo/Redo bug in Ketcher's Monomer Creation Wizard. It's a tricky little issue, but understanding the steps to reproduce it, the potential causes, and the impact on users is the first step towards getting it fixed. Hopefully, the Ketcher team will squash this bug soon, making the software even more reliable and user-friendly for all of us! Keep an eye out for updates, and happy chemistry-ing!

Undo/Redo functionality is a cornerstone of any user-friendly software, enabling users to correct mistakes and explore different options without fear of permanently altering their work. In the context of chemical structure editors like Ketcher, this functionality is particularly crucial. Users often make complex modifications to molecules, and the ability to easily undo and redo these changes is essential for an efficient workflow. However, the bug we've discussed today highlights a potential pitfall in the implementation of this functionality within Ketcher's Monomer Creation Wizard. When users enter this wizard and subsequently cancel without creating a monomer, the expected behavior is that the Undo/Redo actions should restore the canvas state to its precise condition before the wizard was opened. Unfortunately, the observed behavior deviates from this expectation, with Undo/Redo actions inconsistently revealing or restoring parts of the previously selected structure. This discrepancy not only disrupts the user experience but also raises concerns about data integrity, as it creates the impression that the structure has been altered even though no changes were committed through the wizard. The implications of this bug extend beyond mere inconvenience; it can lead to wasted time, potential errors, and a decrease in overall productivity. For researchers, educators, and students alike, a reliable Undo/Redo functionality is paramount for maintaining a smooth and error-free workflow.

Delving Deeper into the Monomer Creation Wizard and its Interaction with Undo/Redo

The Monomer Creation Wizard in Ketcher is a powerful tool designed to facilitate the creation of complex molecules by allowing users to define and incorporate custom monomer units. This wizard streamlines the process of building polymers and other intricate structures, making it an indispensable feature for researchers in various fields. However, the reported bug underscores the intricate interplay between the wizard's internal operations and the overarching Undo/Redo mechanism. When a user invokes the wizard, Ketcher likely creates a temporary snapshot of the current canvas state to enable modifications within the wizard's environment without directly altering the main canvas. This snapshot serves as a sandbox where the user can experiment with different monomer designs and modifications. Upon canceling the wizard, the expectation is that this temporary snapshot should be discarded, and the canvas should revert to its original state, as if the wizard was never opened. The Undo/Redo stack, which meticulously records the history of actions performed on the canvas, plays a pivotal role in this process. Ideally, the cancellation of the wizard should not leave any residual traces in the Undo/Redo stack, ensuring a clean and predictable rollback. However, the reported bug suggests that this synchronization between the wizard's cancellation and the Undo/Redo stack is not seamless. The inconsistent restoration of selected structure parts indicates that some vestige of the wizard's operations is being inadvertently captured in the Undo/Redo history. This could stem from a variety of factors, including improper state management within the wizard, mishandling of events triggered during cancellation, or a flawed interaction between the wizard's internal state and the global Undo/Redo stack. Addressing this issue requires a meticulous examination of the code pathways involved in the wizard's operation, focusing on how changes are tracked, how the state is reverted upon cancellation, and how the Undo/Redo stack is updated during these processes. It's a puzzle that demands a thorough understanding of Ketcher's architecture and its underlying mechanisms for managing user actions.

Exploring the Technical Facets: State Management, Event Handling, and the Undo/Redo Stack

At the heart of this bug lies a complex interplay of technical components, each playing a crucial role in ensuring the integrity of Ketcher's user experience. State management, the backbone of any interactive application, dictates how the application's internal state is captured, modified, and restored. In the context of the Monomer Creation Wizard, effective state management is paramount for preserving the canvas's condition before, during, and after the wizard's operation. When the wizard is invoked, a snapshot of the current state must be taken to allow modifications within the wizard without directly impacting the main canvas. Upon cancellation, this snapshot must be discarded, and the canvas should revert to the state captured in the snapshot. The bug's manifestation suggests that this state management process is not functioning flawlessly, potentially leading to a partial or inconsistent restoration of the canvas state. Event handling further complicates the equation. User interactions, such as opening, modifying, and canceling the wizard, trigger a cascade of events that the application must meticulously process. Each event carries critical information about the user's intent and the necessary actions to be taken. The cancellation event, in particular, requires careful handling to ensure that all temporary changes made within the wizard are discarded and the application's state is correctly reverted. A flaw in the event handling mechanism could lead to the improper propagation of the cancellation event, resulting in a desynchronization between the wizard's state and the canvas's state. The Undo/Redo stack, a fundamental feature of Ketcher, adds another layer of complexity. This stack maintains a chronological record of user actions, enabling users to seamlessly undo and redo changes. The stack's integrity hinges on the correct capture and restoration of application states at each step. When the wizard is canceled, the Undo/Redo stack should ideally remain untouched, preserving the history of actions performed before the wizard was invoked. However, the bug's symptoms suggest that the cancellation process might be inadvertently leaving traces in the Undo/Redo stack, leading to the inconsistent restoration behavior. Rectifying this bug necessitates a comprehensive audit of Ketcher's code, focusing on the interplay between state management, event handling, and the Undo/Redo stack. It's a technical challenge that demands a deep understanding of Ketcher's architecture and its mechanisms for managing user actions and application states.

Keywords

Ketcher, bug, Undo/Redo, Monomer Creation Wizard, partial selection, canvas behavior, unexpected behavior, restore canvas state, Windows 11, Chrome, version 3.7.0-rc.1, version 1.35.0-rc.1, state management, event handling, Undo/Redo stack, testing, software development, chemical structure, monomer structure, data integrity, user experience.