<search string="Burndown Chart">
                <field name="tag_ids"/>
                <field name="user_ids"/>
                <field name="stage_id"/>
                <field name="is_closed"/>
                <field name="project_id"/>
                <field name="milestone_id" groups="project.group_project_milestone"/>
                <field name="partner_id" filter_domain="[('partner_id', 'child_of', self)]"/>
                <separator/>
                <filter string="My Tasks" name="my_tasks" domain="[('user_ids', 'in', uid)]"/>
                <filter string="Unassigned" name="unassigned" domain="[('user_ids', '=', False)]"/>
                <separator/>
                <filter name="filter_date" date="date" string="Date" default_period="year,year-1"/>
                <filter name="filter_last_stage_update" date="date_last_stage_update"/>
                <filter name="filter_date_deadline" date="date_deadline"/>
                <filter string="Last Month" invisible="1" name="last_month" domain="[('date','&gt;=', (context_today() - datetime.timedelta(days=30)).strftime('%Y-%m-%d'))]"/>
                <separator/>
                <filter string="Open Tasks" name="open_tasks" domain="[('is_closed', '=', 'open')]"/>
                <filter string="Closed Tasks" name="closed_tasks" domain="[('is_closed', '=', 'closed')]"/>
                <group expand="0" string="Group By">
                    <filter string="Date" name="date" context="{'group_by': 'date'}"/>
                    <filter string="Stage (Burndown Chart)" name="stage" context="{'group_by': 'stage_id'}"/>
                    <filter string="Is Closed (Burn-up Chart)" name="is_closed" context="{'group_by': 'is_closed'}"/>
                </group>
            </search>