Click on Add Button in Reconciler does nothing in some cases

The Add button in the TEditor's reconciler is enabled but then does nothing when you click it.

1) Create a new view in ModelExplorer. Open the TEditor.
2) Enter SELECT null AS X - then save.
3) Open the Reconciler. The SQL Symbols Add button is enabled, but does nothing when you click it.

The Add button is supposed to show all of the columns available in the FROM tables. However in this case there are no tables. We should disable the button in this case.