Created attachment 178417 [details]
What hapens when closing an application, as you can see, the extra space where it's icon was, is left there instead of being removed.

SUMMARY
When creating a new panel with the settings align centre, non-floating, auto-hiding and adding the "Icons Only Task Manager" widget to it, the panel will not correctly resize according to the amount of icons present on the widget, until you force it to re-evaluate it's size by hovering your mouse over it.

STEPS TO REPRODUCE
1. Create a new empty panel
2. Set it's settings to "Align centre, non-floating, dodge windows"
3. Add the "Icons Only Task Manager" widget to it
4. Launch an application that increases the length of the panel
5. Close the application
6. The panel now keeps an empty space instead of shrinking back down until the mouse is hovered over it

OBSERVED RESULT
The panel does not shrink back down to the correct size when closing applications.

EXPECTED RESULT
The panel should shrink back down the the correct size when closing applications.

SOFTWARE/OS VERSIONS
Linux: Fedora Linux 41 (KDE Spin)
KDE Plasma Version: 6.3.0
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION
The size of the panel works correctly when it's increased, i.e, when launching a new application, it's only when closing applications, where it needs to shrink back down, that doesn't work.