Please check the following:
- Click on Tables node in your current schema
- Right-click on a table and choose Describe. A new window is opened with a lot of buttons in the taskbar.
- Try click on 'Alter Selected Table, ‘Analyze Table’, etc… ‘Estimate Size’, ‘Show Table in ER Diagram’, etc, etc…
- All these new pop-up windows appear behind the current window and there is no way to bring them to front!