pos/pos_to_weight_by_product_uom/views/view_uom_category.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2017 Grap, OCA   
     License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl). -->

<odoo>

    <record id="view_uom_category_form" model="ir.ui.view">
        <field name="model">uom.category</field>
        <field name="inherit_id" ref="uom.product_uom_categ_form_view"/>
        <field name="arch" type="xml">
            <field name="name" position="after">
                <field name="to_weigh" />
                <button name="action_recompute_to_weigh" string="Set 'to weigh' in each product of this category" type="object"/>
            </field>
        </field>
    </record>

    <record id="view_uom_category_tree" model="ir.ui.view">
        <field name="model">uom.category</field>
        <field name="arch" type="xml">
            <tree>
                <field name="name"/>
                <field name="to_weigh" />
            </tree>
        </field>
    </record>

</odoo>