test-addons-11/project_timesheet_matrix/wizard/project_timesheet_matrix_wiz.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

  <record id="project_timesheet_matrix_wiz" model="ir.ui.view">
    <field name="name">project.timesheet.matrix.wiz</field>
    <field name="model">project.timesheet.matrix.wiz</field>
    <field name="type">form</field>
    <field name="arch" type="xml">
      <form>
        <field name="line_ids" widget="x2many_2d_matrix" field_x_axis="date" field_y_axis="user_id" field_value="unit_amount">
          <tree>
            <field name="date" widget="date"/>
            <field name="user_id"/>
            <field name="unit_amount" widget="float_time"/>
          </tree>
        </field>
      </form>
    </field>
  </record>

</odoo>