Openerp SA doesnot support that openoffice plugin module anymore so dont wait for an update. Webkit reports module is chosen for future reporting engine as it is html based and fast.If you need openoffice reports I recommend you aeroo reports module.
Indeed the plugin is not compatible with LibreOffice4.
However, it is still compatible with the last version of OpenOffice. Therefore you can have both programs installed: - Openoffice to use the report designer - LibreOffice 4 to benefit from the new features (in other contexts than OpenERP report design)
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