tdf#91818 disable scrollbar in Start Center when it isn't needed

Change-Id: Ib3b7be6dd93a7f1c75f01ffe53ff7f7c19b14342
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/92773
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Reviewed-by: Roman Kuznetsov <antilibreoffice@gmail.com>
diff --git a/sfx2/source/control/thumbnailview.cxx b/sfx2/source/control/thumbnailview.cxx
index f3488e4..61a7d8f 100644
--- a/sfx2/source/control/thumbnailview.cxx
+++ b/sfx2/source/control/thumbnailview.cxx
@@ -396,6 +396,7 @@ void ThumbnailView::CalculateItemPositions (bool bScrollBarUsed)
            nPageSize = 1;
        mpScrBar->SetPageSize( nPageSize );
        mpScrBar->Show( mbScroll );
        mpScrBar->Enable( mbScroll );
    }

    // delete ScrollBar