Several programs, including Designer, create files with the .adb extension.
Use the File Association tab in the Preferences dialog box to specify Designer as the default program for files with the .adb extension. Doing so starts Designer whenever a file with the .adb extension is double clicked.
You must have rights to modify the HKEY_CLASSES_ROOT of the registry of the machine to set Designer file association. If you do not have rights to modify the registry, Designer ignores your settings.
To associate .adb files with the Designer application:
From the File menu, choose Preferences.
Select Check the default file association (.adb) at startup check box to associate .adb files with the Designer application. Clear the box if you do not want Designer to start when clicking a file with the .adb extension.
Click OK.