tdf#130845 sidebar widget visible when sidebar collapsed

default to "false" and track the parent widget clipping/visibility
instead of "true" which makes it unconditionally visible

Change-Id: I1f8cec2b07ac20c33ff09cc278424d7e20199946
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/89552
Tested-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/vcl/unx/gtk3/gtk3gtkinst.cxx b/vcl/unx/gtk3/gtk3gtkinst.cxx
index ad19e1d..f1d28a2 100644
--- a/vcl/unx/gtk3/gtk3gtkinst.cxx
+++ b/vcl/unx/gtk3/gtk3gtkinst.cxx
@@ -13975,7 +13975,7 @@ weld::Builder* GtkInstance::CreateInterimBuilder(vcl::Window* pParent, const OUS
    // support GtkWidgets within a vcl::Window
    SystemWindowData winData = {};
    winData.bClipUsingNativeWidget = true;
    auto xEmbedWindow = VclPtr<SystemChildWindow>::Create(pParent, 0, &winData, true);
    auto xEmbedWindow = VclPtr<SystemChildWindow>::Create(pParent, 0, &winData, false);
    xEmbedWindow->Show();
    xEmbedWindow->set_expand(true);