SQL Developer can start a new tab every time you select a database object to view; but, you will have to close the tab manually. Set this in: Tools->Preferences->Database->ObjectViewer->Automatically Freeze Object Viewer Windows
Create a diagram for existing database schema or its subset as follows: Click File → Data Modeler → Import → Data Dictionary. Select a DB connection (add one if none). Click Next. Check one or more schema names. Click Next. Check one or more objects to import. Click Next. Click Finish. The ERD is displayed. … Read more