Resolves: tdf#143795 trigger layout when content changes

Change-Id: I9ec19b55f2b46ac8dd1415f45d5e0368fa52fbfd
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120366
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/sd/source/ui/sidebar/SlideBackground.cxx b/sd/source/ui/sidebar/SlideBackground.cxx
index e225d45..97a1672 100644
--- a/sd/source/ui/sidebar/SlideBackground.cxx
+++ b/sd/source/ui/sidebar/SlideBackground.cxx
@@ -450,6 +450,10 @@ void SlideBackground::Update()
        default:
            break;
    }

    // Need to do a relayouting, otherwise the panel size is not updated after show / hide controls
    if (m_pPanel)
        m_pPanel->TriggerDeckLayouting();
}

void SlideBackground::UpdateMarginBox()