Recently I was working on Watermark feature for LibreOffice Writer. In case of TSCP Classification it was possible to add "Confidential" watermark in the document background. I extended that with possibility to add custom text, font family, color, transparency level and angle. Additional dialog was introduced in the menubar under "Insert" > "Watermark...".
I improved also export and import for that kind of shapes from .dotx files. Now font-family is correctly loaded:
RTF import also was improved, before Watermark was visible as a plain text: