diff --git a/addons/project/project.py b/addons/project/project.py
index c30ddce74e9..68b987451a6 100644
--- a/addons/project/project.py
+++ b/addons/project/project.py
@@ -128,7 +128,7 @@ class project(osv.osv):
         'analytic_account_id': fields.many2one('account.analytic.account', 'Analytic Account', help="Link this project to an analytic account if you need financial management on projects. It enables you to connect projects with budgets, planning, cost and revenue analysis, timesheets on projects, etc.", ondelete="cascade", required=True),
         'priority': fields.integer('Sequence', help="Gives the sequence order when displaying the list of projects"),
         'warn_manager': fields.boolean('Warn Manager', help="If you check this field, the project manager will receive a request each time a task is completed by his team.", states={'close':[('readonly',True)], 'cancelled':[('readonly',True)]}),
-        'members': fields.many2many('res.users', 'project_user_rel', 'project_id', 'uid', 'Project Members', help="Project's member. Not used in any computation, just for information purpose.", states={'close':[('readonly',True)], 'cancelled':[('readonly',True)]}),
+        'members': fields.many2many('res.users', 'project_user_rel', 'project_id', 'uid', 'Project Members', help="Project's member. Not used in any computation, just for information purpose, but a user has to be member of a project to add a the to this project.", states={'close':[('readonly',True)], 'cancelled':[('readonly',True)]}),
         'parent_id': fields.many2one('project.project', 'Parent Project'),
         'tasks': fields.one2many('project.task', 'project_id', "Project tasks"),
         'planned_hours': fields.function(_progress_rate, multi="progress", method=True, string='Planned Time', help="Sum of planned hours of all tasks related to this project and its child projects.",
diff --git a/addons/project/project_view.xml b/addons/project/project_view.xml
index a05d16071e5..5c7fdb72cca 100644
--- a/addons/project/project_view.xml
+++ b/addons/project/project_view.xml
@@ -223,7 +223,7 @@
                 <form string="Task edition">
                     <group colspan="6" col="6">
                         <field name="name" select="1"/>
-                        <field name="project_id" select="1"  on_change="onchange_project(project_id)" domain="[('user_id','=',uid)]"/>
+                        <field name="project_id" select="1"  on_change="onchange_project(project_id)" domain="['|',('user_id','=',uid),('members','=',uid)]" />
                         <field name="total_hours" widget="float_time"/>
                         <field name="date_deadline" attrs="{'readonly':[('state','in',['done', 'cancelled'])]}"/>
                         <field name="user_id" select="1" attrs="{'readonly':[('state','in',['done', 'cancelled'])]}"/>
diff --git a/addons/project_timesheet/project_timesheet.py b/addons/project_timesheet/project_timesheet.py
index 00a28ce2b50..141b5756271 100644
--- a/addons/project_timesheet/project_timesheet.py
+++ b/addons/project_timesheet/project_timesheet.py
@@ -28,16 +28,7 @@ from tools.translate import _
 
 class project_project(osv.osv):
     _inherit = 'project.project'
-    def onchange_partner_id(self, cr, uid, ids, part=False, context=None):
-        result = super(project_project, self).onchange_partner_id(cr, uid, ids, part, context=context)
-        if result.get('value', False):
-            try:
-                d = self.pool.get('ir.model.data').get_object_reference(cr, uid, 'hr_timesheet_invoice', 'timesheet_invoice_factor1')
-                if d:
-                    result['value']['to_invoice'] = d[1]
-            except ValueError, e:
-                pass
-        return result
+    
 project_project()
 
 class project_work(osv.osv):
diff --git a/addons/project_timesheet/project_timesheet_view.xml b/addons/project_timesheet/project_timesheet_view.xml
index f8c25f4cb33..56dfa068b21 100644
--- a/addons/project_timesheet/project_timesheet_view.xml
+++ b/addons/project_timesheet/project_timesheet_view.xml
@@ -11,7 +11,7 @@
                     <group colspan="4" col="4">
                         <separator colspan="4" string="Invoicing Data"/>
                         <field name="pricelist_id" domain="[('type','=','sale')]" widget="selection"/>
-                        <field name="to_invoice" widget="selection" string="Invoice Task Work"/>
+                        <field name="to_invoice" widget="selection" string="Invoice Task Work" attrs="{'required':[('partner_id','!=',False)]}"/>
                         <field name="amount_max" groups="base.group_extended"/>
                         <field name="amount_invoiced" groups="base.group_extended"/>
                     </group>