[FIX]hr_negative_leave:fix leave types available when creating a leave request

hr_negative_leave/views/hr_leave_views.xml

@@ -5,17 +5,26 @@
         <field name="inherit_id" ref="hr_holidays.hr_leave_view_form" />
         <field name="arch" type="xml">
             <xpath expr="//field[@name='holiday_status_id']" position="attributes">
+                <!-- Pseudo-code for the domain:
+                    if requires_allocation == 'no': 
+                        ok
+                    elif has_valid_allocation and virtual_remaining_leaves > 0 and max_leaves > 0: 
+                        ok 
+                    elif allows_negative == True:
+                        ok
+                    else: 
+                        refuse
+                -->
                 <attribute name="domain">[
-                    '|',
+                    '|', '|',
                     ('requires_allocation', '=', 'no'),
                     '&amp;',
-                    ('has_valid_allocation', '=', True),
-                    '|',
-                    ('allows_negative', '=', True),
-                    '&amp;',
-                    ('virtual_remaining_leaves', '&gt;', 0),
-                    ('allows_negative', '=', False),
-                    ]</attribute>
+                        ('has_valid_allocation', '=', True),
+                        '&amp;',
+                            ('virtual_remaining_leaves', '&gt;', 0),
+                            ('max_leaves', '&gt;', 0),
+                    ('allows_negative', '=', True)
+                ]</attribute>
             </xpath>
         </field>
     </record>