Adding constraint column does not remove it from the "Available Table Columns" box (4318370)

When trying to create a Foreign Key constraint, the same Table column can be added innumerous times as a Constrained Column in the Create Constraint screen.

Steps to Reproduce:

1. Open the Schema Browser and select a table.
2. Click the "Add constraints to this table" button.
3. Select a column from "Available Table Columns" and click the ">" to move it to right side. Column is removed from left as expected.
4. Select a reference table but do not select a column.
5. Go back to "This Table" tab.

WORKAROUND:
None.

STATUS:
Waiting for fix in a future release of Toad for Oracle.