GUI: List scroll arrows don't work, recent regression

[sluicebox]

Clicking the top or bottom scroll arrow in a list no longer scrolls by one, but instead scrolls an entire page as if the scrollbar area was clicked. Game launcher, save/restore screen...

Recent GUI regression in master, not in the previous release.

[tunnelsociety]

$ git bisect bad
cb71d7b6cf946945add11834a6d957726d27dbc3 is the first bad commit

commit cb71d7b6cf946945add11834a6d957726d27dbc3 (HEAD)
Date:   Sat Apr 18 01:50:38 2026 +0530

    GUI: Implement Fluid scroll in Launcher List

 gui/widgets/groupedlist.cpp | 19 ++++++++++++++++---
 gui/widgets/list.cpp        | 46 +++++++++++++++++++++++++++++++++++-----------
 gui/widgets/list.h          |  3 +++
 3 files changed, 54 insertions(+), 14 deletions(-)

[bluegr]

PR 7450:

​https://github.com/scummvm/scummvm/pull/7450