When a combobox is opened, the list of entries is expected to be positioned so that the currently selected one is exactly where that value was shown before the list was opened.
See the two screenshots demonstrating the problem.
Note that even though the mouse pointer isn't visible, I did not move the mouse between making these two screenshots. It was at the top part of the closed combobox. So when I clicked to open it, it automatically focused the previous entry. Clicking once again would choose that entry, modifying my settings. Expected: if I click again without moving the mouse, my settings shouldn't change.
It seems that the height of the additional top/bottom paddings with the rounded corners isn't properly taken into account.
(The screenshots were taken in gnome-terminal's preferences window, but this is irrelevant.)
ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: yaru-theme-gtk 18.10.5
ProcVersionSignature: Ubuntu 4.18.0-8.9-generic 4.18.7
Uname: Linux 4.18.0-8-generic x86_64
ApportVersion: 2.20.10-0ubuntu11
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Tue Oct 2 23:24:58 2018
InstallationDate: Installed on 2016-11-09 (691 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
PackageArchitecture: all
SourcePackage: yaru-theme
UpgradeStatus: Upgraded to cosmic on 2018-09-25 (6 days ago)
Status changed to 'Confirmed' because the bug affects multiple users.