SnapOnInput And RepositionCursorWithMouse Bug Clicking Scrolls To Bottom

Hey everyone! Today, we're diving deep into a quirky bug in the Windows Terminal that occurs when the snapOnInput and repositionCursorWithMouse settings are both enabled. This issue causes the terminal to scroll to the bottom whenever you try to select text after scrolling up, which can be super frustrating, especially when you're trying to copy something important. Let's break down what's happening, how to reproduce it, and what the expected behavior should be. This comprehensive guide aims to provide a detailed understanding of the bug, its implications, and potential workarounds, making it a valuable resource for users and developers alike. Understanding the intricacies of this bug not only helps in troubleshooting but also sheds light on the complex interplay between different terminal settings.

Understanding the Bug

When snapOnInput and repositionCursorWithMouse are both set to true in Windows Terminal, a peculiar issue arises. Specifically, if you scroll up in the terminal and then attempt to select text using the left mouse click, the terminal instantly scrolls back to the bottom. This behavior is particularly noticeable when the terminal is displaying output from applications that continuously generate text, such as the ping command or during an SSH session. This scrolling issue disrupts the user's ability to select and copy text from the terminal output, hindering productivity. The unexpected jump to the bottom of the terminal can be jarring, especially when trying to review or extract information from previous outputs. The combination of these two settings, designed to enhance user experience, inadvertently leads to this disruptive behavior.

This bug is not just a minor annoyance; it significantly impacts the usability of the terminal. Imagine trying to debug a complex issue by reviewing logs, only to have the terminal constantly scroll to the bottom every time you try to select a piece of text. This makes it incredibly difficult to pinpoint the exact information you need. Moreover, the error sound that sometimes accompanies this issue, particularly during SSH sessions, adds another layer of frustration. The interplay between snapOnInput and repositionCursorWithMouse seems to create a conflict that results in this erratic scrolling behavior. Therefore, understanding the root cause of this bug is crucial for both users seeking workarounds and developers aiming to fix it.

What are snapOnInput and repositionCursorWithMouse?

Before we dive deeper, let's clarify what these settings actually do. The snapOnInput setting is designed to keep the terminal view focused on the latest input, automatically scrolling to the bottom whenever new input is received. This is useful for monitoring real-time output, ensuring you always see the most recent information. On the other hand, repositionCursorWithMouse aims to improve mouse interaction within the terminal, allowing the cursor to be repositioned to the location of the mouse click. This feature is intended to make text selection and other mouse-based actions more intuitive. However, when these two settings are combined, they create a conflict that triggers the scrolling bug. The intention behind each setting is to enhance the user experience, but their interaction reveals an unforeseen issue. Understanding the purpose of each setting helps in appreciating the complexity of the problem and the challenge in finding a solution that preserves the intended functionality while eliminating the bug.

Steps to Reproduce the Bug

To see this bug in action, follow these simple steps using the ping command, a common network utility that continuously outputs data. This example provides a clear and reproducible scenario, making it easier for others to confirm the bug and for developers to investigate the issue. The use of a widely available tool like ping ensures that anyone can replicate the steps without needing specialized software or configurations. This reproducibility is crucial for effective bug reporting and debugging.

1. First, ensure both snapOnInput and repositionCursorWithMouse are set to true in your Windows Terminal settings. This is the crucial first step, as the bug only manifests when both settings are enabled. You can find these settings in the settings.json file or through the terminal's settings UI. Double-checking these settings is important to ensure that the bug reproduction steps are followed correctly. The settings file can be accessed by clicking on the settings icon in the terminal or by typing Ctrl+,. Make sure to save the changes after modifying the settings.
2. Restart the terminal to apply the new settings. This step is necessary because some settings changes require a restart to take effect. Restarting ensures that the terminal is running with the correct configuration, preventing any discrepancies in behavior. A clean restart helps in isolating the bug and ensuring that it is not caused by any residual state from the previous session. This step is often overlooked, but it is critical for accurate bug reproduction.
3. Run ping -t 127.0.0.1 (or any command with continuous output) and wait for the output to fill the window, requiring scrolling. The ping -t 127.0.0.1 command sends continuous ping requests to your local machine, generating a steady stream of output. This continuous output is essential for triggering the bug, as it creates the need for scrolling. Alternatively, you can use other commands or applications that produce a continuous stream of output. The goal is to fill the terminal window quickly so that you have enough content to scroll through. Adjusting the window size can also help in accelerating the filling of the terminal.
4. Scroll up in the terminal window. Use your mouse wheel or the scrollbar to navigate up in the terminal output. This action moves the viewport away from the bottom of the terminal, which is the starting point for triggering the bug. Scrolling up is a key step, as the bug only occurs when you are viewing historical output. Ensure that you scroll up far enough to see older output lines. The amount you need to scroll depends on the size of the terminal window and the rate of output generation.
5. Attempt to select text with the left mouse click. This is the moment when the bug manifests. Try to click and drag to select any text in the scrolled-up area. As soon as you click, the terminal will instantly scroll back to the bottom, disrupting your selection. The scrolling occurs regardless of where you click in the terminal window, making it difficult to select any text above the current viewport. This unexpected behavior is the core of the bug and the main source of frustration for users.

By following these steps, you should be able to reliably reproduce the scrolling bug, confirming that it is indeed an issue with the interaction between snapOnInput and repositionCursorWithMouse. This reproducible scenario provides a solid basis for further investigation and debugging.

Visual Confirmation

The original bug report included a screencap demonstrating the issue. The video clearly shows the terminal scrolling to the bottom the moment the user attempts to select text after scrolling up. Visual confirmation like this is invaluable in understanding the bug's behavior and impact. The screencap also highlighted an interesting observation: the scrolling doesn't occur when trying to select the