The links you reference are very old, and one (actually for JDeveloper) predates the existence SQL Developer. The automatic reload works fine for me, both for Notepad and Notepad++. Since it also works for you with the 3.2.2 release, I can only assume your user settings for 4.0.2 got corrupted somehow. If you migrated them from 3.2.20.09.87 or some other release, I recommend...
1. Exiting SQL Developer
2. Deleting or renaming %APPDATA%\SQL Developer\system220.127.116.11.21
3. Keep in mind that Windows by default, considers the AppData folder portion of C:\Users\<username>\AppData to be hidden.
4. Start SQL Developer and skip past any prompts about migration of user settings.
Hope this helps,
SQL Developer Team