When I modify a file externally (eg with Notepad++), the Automatically Reload Externally Modified Files feature does not work. This is regardless of whether or not Automatically Reload Externally Modified Files or Silently Reload When File Is Unmodified checkboxes are checked in Environment Preferences.
Oracle SQL Developer 4.0.2.15, build 15.21, x64
Java Platform 1.7.0_55
Windows 7 Professional 64bit
I have noticed other forum threads talking about this, but they have all been archived:
https://community.oracle.com/message/1244946#1244946
Current workaround - use SQL Developer 3.2.20.09 instead.