Resolves: tdf#123711 measure scrollbar for optimal width

Change-Id: I30225124e44e8a6290270ecba5024f36508817d3
Reviewed-on: https://gerrit.libreoffice.org/68429
Tested-by: Jenkins
Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>
diff --git a/vcl/source/treelist/treelistbox.cxx b/vcl/source/treelist/treelistbox.cxx
index 6aea58a..0ece3b5 100644
--- a/vcl/source/treelist/treelistbox.cxx
+++ b/vcl/source/treelist/treelistbox.cxx
@@ -3133,6 +3133,10 @@ Size SvTreeListBox::GetOptimalSize() const
    }
    long nMinWidth = nMinWidthInChars * approximate_char_width();
    aRet.setWidth( std::max(aRet.Width(), nMinWidth) );

    if (GetStyle() & WB_VSCROLL)
        aRet.AdjustWidth(GetSettings().GetStyleSettings().GetScrollBarSize());

    return aRet;
}