Bugs in my customized version of a popular gantt chart

[Petanek3333]

Hello Community,

I’ve been working on developing a Gantt chart using Madison Giammaria’s @giammariam  template. It is great already but I had to develop some other custom features so I’ve successfully implemented several functionalities—partly using my own knowledge and partly with AI assistance. However, I’ve now hit a roadblock with three bugs that are preventing the visual from functioning as intended.

I’d love any help in resolving them—fixing just one would be a great step forward, but solving all three would be a huge relief! 😊

Bug 1: Expanding/Collapsing Tasks in Bulk

I wanted to create a custom bulk expand/collapse button to toggle all tasks at once.

However, unlike the original template, if I expand all tasks and then try to collapse just one, it collapses all of them instead of only the selected one.

I suspect the issue lies in the hierarchy_initial transformations (lines 2224–2238) in my Vega code, but I haven’t been able to get it working as intended.

Bug 2: Horizontal Scrolling, Zooming, and Task Visibility Issues

I had to tweak the template to properly display the Today line, as I couldn’t get it working from the original setup. However, my implementation may have introduced unexpected issues.

Problem 1: Tasks Not Visible in Default View
For example, in the image below, Task 95 (starting on March 19, 2023) should be partially visible, but it isn’t.

If I scroll horizontally or zoom out slightly, it suddenly appears. Expanding the task doesn’t reveal the subtasks either.

I suspect the issue is related to how the x-axis range is set before and after the min/max task dates. I attempted to configure default views for different task lengths using the configDateStepSizePercentInitial signal (lines 25–28), but that didn’t resolve it.

Problem 2: Missing Tasks on Horizontal Scroll
If I scroll left (Shift + Mouse Wheel), I expect to see tasks from 2022, but they don’t appear even though they should.

This is my biggest issue—if anyone has insights on what might be causing this, I’d be incredibly grateful!

Bug 3: Bottom Tasks Not Expandable

This issue also exists in the original template:

If the last task in the visual reaches the bottom of the canvas, the task is not clickable, preventing expansion. The only workaround is to collapse some other tasks first, but that negatively affects the user experience.

I’d really appreciate any advice, guidance, or fixes for these issues. Even just pointing me in the right direction would be incredibly helpful.

Sample file: https://www.dropbox.com/scl/fi/dcrciewmls9dj3fqpc4m8/sample_data_tasks.pbix?rlkey=65tjgo587u9991jaj7...

Thanks in advance, and have a great day!
Petr