Empty combo "Start from" at "New Theme" pop-up

Steps to reproduce:

• Access to View Designer
• Click on "UI" tab
• Click on "Themes"
• Add on "Add" button
• "New Theme" pop-up is shown
• Click on "Start from" combo

The pop-up is empty. No options to choose or option to type some text

NOTE: If you provide a theme name and click on the "Create" button the pop-up is never closed.

Tested on Chrome: Versión 60.0.3112.113 for Mac