QComboBox tests if a horizontal scrollbar is needed before sizing and showing the popup, but QListView only knows whether a scrollbar is needed only after laying itself out during the initial show and paint event. So test whether the need has arisen as part of this initial layout, and then provide the additional space. Resizing the widget after showing it is not ideal, but in practice makes no visible difference (and it's either way preferable to not being able to access the item covered by the scrollbar). Fixes: QTBUG-93736 Change-Id: I0bf077e18116ce174ae7f9218cb3b0dfa82964e1 Reviewed-by: Andy Shaw <andy.shaw@qt.io> (cherry picked from commit 11e88eaa6df629a2c23a60815a1f7826dd2ac31a) Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>