minor fix

app/main.py

@@ -709,6 +709,7 @@ class AppWindow(FrontWindow):
     def change_view_to(self, to_view):
         self.field_salesman_code_ask.setText('')
         if to_view == 'start_front':
+            self.clear_right_panel()
             self.print_no_commanded()
             self.salesman = {}
             self.order_front.hide()
@@ -1647,7 +1648,7 @@ class AppWindow(FrontWindow):
         return True
 
     def action_source(self):
-        if self._state != 'checkout':
+        if self._state != 'checkout' and self.sources:
             self.dialog_source.exec_()
 
     def action_payment_term(self):