Undoing delete of used action does not set state to used

Steps to reproduce:

• create Qt Widget Application, open the ui file
• create an action and drag it onto the toolbar of the preview
• check the properties of the action (it should be marked as used now)
• hit delete above the ActionEditor - this removes the action from ActionEditor and the toolbar
• type Ctrl+Z

Expected behavior:

• action re-appears inside ActionEditor and toolbar
• action has 'used' state marked again

Current behavior:

• action re-appears inside ActionEditor and toolbar
• 'used' is unchecked and stays so