MultiSelect/Dropdown Panel Size Jumps around on Filter while VirtualScroll is enabled

[mkutowski]

Describe the bug

When using VirtualScroll on a MultiSelect and filtering the menu items, the Panel Height jumps to keep up with all filtered items. This also happens on Dropdown Filtering.

The Issue does currently not exist in v18 and v19 as it was introduced sometime after v17.18.11 where bugfixes to virtualScroll Scroller sizes were introduced.

Here is a video showcasing the issue:

firefox_XQnB1p0TgJ.mp4

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

No response

Reproducer

https://v17.primeng.org/multiselect

Environment

Official PrimeNG v17 MultiSelect "Virtual Scroll" Showcase

Angular version

18

PrimeNG version

v17 (LTS Only)

Node version

No response

Browser(s)

No response

Steps to reproduce the behavior

1. Open the MultiSelect Component Showcase on the PrimeNG Components examples
2. Go to the "Virtual Scroll" Section
3. Click on the MultiSelect Button -> Opens the filter
4. Filter to some Number like "321321" -> Everything is fine
5. Remove the Filter to nothing ""
6. Now type the same Filter "321321" again one by one
7. The Resize bug will now appear

Expected behavior

As before the MultiSelect Panel size should not jump around and cause the Panel to jump large sections. In v18 and v19 you can see the normal behaviour.