muk_web/muk_web_preview/static/src/xml/preview_widgets.xml

<?xml version="1.0" encoding="UTF-8"?>

<!--     
	Copyright (C) 2017 MuK IT GmbH
	
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>. 
-->

<templates>
	<t t-extend="FieldBinaryFile">
        <t t-jquery="a.o_form_uri" t-operation="replace">
	    	<div t-if="widget.get('effective_readonly')">
		    	<button type="button" class="o_binary_preview" aria-hidden="true"><i class="fa fa-file-text-o"></i></button>
		    	<a href="javascript:void(0)" class="o_form_uri"/>
	    	</div>
        </t>
    </t>
</templates>