gtk4: default GtkViewport to can-focus

Change-Id: If4c730cef1782c20f6f8519e77ff336c0e9e692c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/121870
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/vcl/unx/gtk4/convert3to4.cxx b/vcl/unx/gtk4/convert3to4.cxx
index 837a960..b1e1752 100644
--- a/vcl/unx/gtk4/convert3to4.cxx
+++ b/vcl/unx/gtk4/convert3to4.cxx
@@ -418,7 +418,8 @@ ConvertResult Convert3To4(const css::uno::Reference<css::xml::dom::XNode>& xNode
                if (!bChildCanFocus)
                {
                    OUString sParentClass = GetParentObjectType(xChild);
                    if (sParentClass == "GtkBox" || sParentClass == "GtkGrid")
                    if (sParentClass == "GtkBox" || sParentClass == "GtkGrid"
                        || sParentClass == "GtkViewport")
                    {
                        // e.g. for the case of notebooks without children yet, just remove the can't focus property
                        // from Boxes and Grids