Clicking the Cancel button on the beforeNavigation modal dialog, keeps the mask over the navapp

Steps to reproduce:

1. Go to the Experience manager perspective
2. Enter the HAP channel
3. Go to the news menu item
4. Edit a news
5. Change the text in the document
6. Click on the Experience Manager root item
7. On the modal dialog click cancel
8. Go to the projects perspective

Expected result:

The user is taken to the projects perspective

Actual result:

The application is blocked by a mask, so the user cannot click any of the nav items