Naming menu separators in design view is broken

Steps:
1. Create a menu separator in a window's menu bar in the design view
2. Set its object name via either the property inspector or directly from the hierarchy view

Expected: Separator object name updated in hierarchy view, separator object made available as a generated Ui class member.

Actual: Separator object name is updated in property inspector but remains "separator" in hierarchy view. Separator object is not available as a generated Ui class member.