Add TASK_MODIFY_ALL action (addresses vit-project#240)

This action is a first use case (but really just one special case) of bulk editing, which  makes use of the new 'modify_multiple' operation by passing the filter expression that matches all tasks visible in the current view.

vit/actions.py

@@ -38,6 +38,7 @@ def register(self):
         self.action_registrar.register('TASK_DELETE', 'Delete task')
         self.action_registrar.register('TASK_DENOTATE', 'Denotate a task')
         self.action_registrar.register('TASK_MODIFY', 'Modify task (supports tab completion)')
+        self.action_registrar.register('TASK_MODIFY_ALL', 'Modify all tasks currently in view')
         self.action_registrar.register('TASK_START_STOP', 'Start/stop task')
         self.action_registrar.register('TASK_DONE', 'Mark task done')
         self.action_registrar.register('TASK_PRIORITY', 'Modify task priority')

vit/application.py

@@ -178,6 +178,7 @@ def register_managed_actions(self):
         self.action_manager_registrar.register('TASK_DELETE', self.task_action_delete)
         self.action_manager_registrar.register('TASK_DENOTATE', self.task_action_denotate)
         self.action_manager_registrar.register('TASK_MODIFY', self.task_action_modify)
+        self.action_manager_registrar.register('TASK_MODIFY_ALL', self.task_action_modify_all)
         self.action_manager_registrar.register('TASK_START_STOP', self.task_action_start_stop)
         self.action_manager_registrar.register('TASK_DONE', self.task_action_done)
         self.action_manager_registrar.register('TASK_PRIORITY', self.task_action_priority)
@@ -789,6 +790,11 @@ def task_action_modify(self):
             self.activate_command_bar('modify', 'Modify: ', {'uuid': uuid})
             self.task_list.focus_by_task_uuid(uuid, self.previous_focus_position)
 
+    def task_action_modify_all(self):
+        currentviewfilter = self.active_view_filters()
+        ntasks = self.model.get_n_tasks(currentviewfilter)
+        self.activate_command_bar('modify_multiple', 'Modify all (%s tasks): ' % ntasks, {'target': currentviewfilter, 'ntasks': ntasks})
+
     def task_action_start_stop(self):
         uuid, task = self.get_focused_task()
         if task: