Description of problem:
[Machines] The path select drop down box will not sync appearance when pressing down arrow on keyboard

Version-Release number of selected components (if applicable):
cockpit-machines-256-1.el9.noarch
cockpit-258-1.el9.x86_64
libvirt-dbus-1.4.1-5.el9.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Click "Import vm", input "/tmp/" in Disk image

2. Keep on pressing down arrow on keyboard

Actual results:
The drop down box does not scroll down to focus on the current chosen file

Expected results:
The drop down box should scroll down to focus on the current chosen file

Additional info:
Same problem on RHEL8&RHEL9.
It's a bit hard to describe exactly, but when you have a try you will understand what I mean, thank you.