Qt5.1.1 offline installer: Package manager, Update components radio boxes are enabled even though cannot be used

Download and install the Qt5.1.1 offline opensource installer (linux 32-bit installer used while testing).
Start the MaintenanceTool. The radioboxes 'Package manager' and 'Update components' are enabled even though they don't work. If they are selected, a note text appears: "At least one valid and enabled repository required for this action to succeed."
--> bad end user experience. See the attached screen captures.