ComboBox Popup Height and Spacing Issue

ComboBox popup displays with incorrect height, extra space at the bottom and partially cut-off items, even when margins and height are computed dynamically and correctly.

Steps to Reproduce:

1. Open the attached minimal example project.

1. Interact with the ComboBox in the application.

1. Observe the rendered popup list.

Expected Behavior:
The ComboBox popup should display only the specified number of visible items, with appropriate spacing and no extra space or cutoff.

Actual Behavior:

• Extra space appears at the bottom of the popup.

• Some items in the popup are partially cut off.

I have attached example project.